LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


THE 

Manufacture  of  Metallic  Articles 
Electrolytically.  —  Electro-    ~ 
/    Engraving   - 

BY 
DR.  W.  PFANHAUSER 


t  • 


Manufacturer  of  Machinery,  Apparatus  and  Chemical  Prepar- 
ations for  Electroplating  and  Galvanoplastics 


UNIVERSITY  Authorized  English  Translation 


JOSEPH  W.  RICHARDS,  MA,  A.C,  Ph.D. 

Professor  of  Metallurgy,  Lehigh  University ;   Past  President  of 
the  American  Electrochemical  Society 


EASTON,   PA. 

THE  CHEMICAL  PUBLISHING  CO. 
1906 


"' 


COPYRIGHT,  1906,  BY  THE  CHEMICAL  PUBLISHING  Co. 


162340 


MONOGRAPHS 

ON— 

APPLIED  ELECTROCHEMISTRY 

EDITED  BY 

VIKTOR   ENGELHARDT. 

Head  Engineer  and  Chief  Chemist  of  the  Siemens  &  Halske  A.  G., 

Vienna. 

WITH  THE  COOPERATION  OF 
Dr.  E.  Abel,  Chemist  for  the  Siemens  &  Halske  A.  G.,  Vienna. 

E.  G.  Acheson,  President  of  the  International  Acheson  Graphite  Co., 

Niagara  Falls,  N.  Y. 

Dr.  P.  Askenasy,  Superintendent  of  the  Akkumulatorwerke,  Liesing. 

H.  Becker,  Publisher  of  "  L 'Industrie  e"lectro~chimique,  "  Paris. 

Dr.  W.  Borchers,  Professor  at  the  Technical  High  School,  Aachen. 

Sh.  Cowper-Coles,  Publisher  of  "The  Electrochemist  and  Metallur- 
gist," London. 

Dr.  F.  Dieffenbach,  Professor  at  the  Technical  High  School,  Darm- 
stadt. 

Dr.  G.  Erlwein,  Chief  Chemist  of  the  Siemens  &  Halske  A.  G.,  Berlin. 

H.  Friberg,  Engineer  of  the  Siemens  &  Halske,  A.  G.,  Berlin. 

H.  Gall,  Director  of  the  Societe  d 'Electrochimie,  Paris. 

F.  E.  Giinther,  Mining  Engineer,  Aachen. 

Dr.  F.  Haber,  Professor  at  the  Technical  High  School,  Karlsruhe. 

Dr.  C.  Haussermann,  Professor  at  the  Technical  High  School,  Stutt- 
gart. 

Dr.  R.  Hammerschmidt,  Electrochemist,  Charlottenburg. 

Dr.  G.  Hausdorff,  Registeed  Chemist,  Essen. 

Dr.  K.  Kellner,  General  Drirector,  Vienna. 

A.  Krakau,  Professor  of  theElectrochemical  Institute,  St.  Petersburg. 

Dr.  H.  Landolt,  Director  of  the  Society  for  Electrochemical  Industry, 
Turgi. 

Dr.  M.  Le  Blanc,  Professor  at  the  Technical  High  School,  Karlsruhe. 

C.  Liebenow,  Engineer,  Berlin. 

Dr.  R.  Lorenz,  Professor  at  the  Swiss  Polytechnic,  Zurich. 

Dr.  R.  Lucion,  Director  of  Solvay  &  Co.,  Brussels. 

A.  Minet,  Publisher  of  "  L 'Electrochimie, "  Paris. 

A.  Nettel,  Engineer,  Berlin. 

H.  Nissenson,  Director  of  Akt.-Ges.  of  Stolberg  &  Westfalen, 
Stolberg. 

Dr.  F.  Peters,  Instructor  at  the  Royal  Mining  Academy,  Berlin. 

Dr.  W.  Pfanhauser,  Manufacturer,  Vienna. 

Registered  Chemist  Dr.  O.  Prelinger,  Chemist  of  the  Siemens  & 
Halske  A.  G.,  Vienna. 

Titus  Ulke,  M.  E.,  Electrometallurgical  and  Mining  Engineer  of  the 
Lake  Superior  Power  Co.,  Sault  Ste.  Marie,  Ontario. 

Dr.  Th.  Zettel,  Chief  Chemist  of  Brown-Boveri  &  Co.,  Baden. 
And  other  experts. 


CONTENTS 


PAGE 

I.  HISTORICAL  REVIEW i 

A.  Introduction I 

B.  Advances  in  the  Art i 

II.  BATHS  FOR  COPPER  GALVANOPLASTY 3 

A.  Neutral  Bath 3 

B.  Work  of  Chassy 3 

C.  Foerster's  Work  on  Quautitive  Precipitation  of  Copper 4 

D.  Studies  by  Hiibl,  1886 •  •  •  • 6 

III.  PHYSICAL  PROPERTIES  OF  THE  COPPER  DEPOSIT 14 

A.     Hiibl's  Investigations 15 

IV.  BEHAVIOR  OF  COPPER  ANODES 25 

V.  CONSTANTS  OF  THE  BATH  AND  CALCULATION  OF  THE  AMOUNT 

OF  DEPOSIT 28 

VI.  INDUSTRIAL  PLANTS .32 

VII.  PARTICULAR  DEVICES  FOR  SPECIAL  PURPOSES.     PRODUCTION 

OF  UNIFORM  DEPOSITS 37 

A.  Process  of  Bauer 39 

B.  Process  of  Anderson 39 

C.  Wurttemberg  Process 40 

D.  Dumoulin  Process 42 

E.  Method  of  the  French  Copper  Company 43 

F.  Devices  for  Loosening  of  the  Precipitates 43 

G.  Process  of  Sutherland 43 

H.  Process  of  Reinfeld 44 

I.  Method  of  Holl 44 

J.  Blmore's  Process 45 

K.  Nussbaum's  Process 46 

Iv.  Collapsible  Forms 46 

M.  Klmore's  Process 47 

N.  Collapsible  Moulds  of  Gerhardi  &  Co. 49 

VIII.  MANUFACTURE  OF  METALLIC  POWDERS  AND  THE  LIKE 52 

A.  Process  of  the  Societe  Civile 54 

B.  Process  of  Hoepner 55 

C.  Process  of  Hiiber  &  Sachs 60 

IX.  MANUFACTURE  OF  METALLIC  FOIL 61 

A.  Process  of  Reinfeld 61 

B.  Process  of  Kndru weit 61 

C.  Klmore's  Process 63 


Vlll  CONTENTS 

D.  Desolle's  Process  63 

E.  Process  of  Cowper-Coles 64 

F.  Process  of  Landauer  &  Co 64 

G.  Process  of  Brandt  &  Nawrocki 69 

H.  Process  of  Endruweit 70 

I.  Process  of  Schroeder 70 

J.  Sheet  Gold  by  Swan's  Process 72 

K.  Production  of  Plane  Surfaces,  Rieder's  Process 72 

L.   Elmore's  Process 75 

X.  PRODUCTION  OF  WIRE,  &c.  •  •  •> 76 

A.  Process  of  Elkington 76 

B.  Fox's  Process 76 

C.  Acheson's  Process 76 

D.  Tavernier's  Process 77 

E.  Process  of  Swan 78 

F.  Process  of  Sanders 84 

G.  Process  of  Forsythe  and  Fletcher 91 

H.  Process  of  Cowper-Coles  . .  ' 91 

XI.  MANUFACTURE  OF  BODIES  OF  LARGE  SIZE 93 

A.  Process  of  J.  Klein 93 

B.  Nussbaum's  Process 100 

C.  Sutherland's  Process 105 

D.  Elmore's  Process 105 

E.  Process  of  Davis  &  Evans 106 

F.  Process  of  A.  Krueger 106 

XII.  MANUFACTURE  OF  PARABOLIC  MIRRORS 108 

A.  Process   of  the   Elmore  German   and  Austro-Hungarian  Metal 

Company,  Limited,  and  P.  E.  Preschlin 108 

B.  Process  of  Cowper-Coles 108 

XIII.  MANUFACTURE  OF  TUBES 117 

A.  Process  of  the  French  Copper  Society 123 

B.  Process  of  Dumoulin 125 

XIV.  ELECTROLYTIC  ETCHING 130 

A.  Burdette's  Process 131 

B.  Hall  &  Thornton  Process 133 

XV.  ELECTROLYTIC  ENGRAVING 138 

A.  Introduction 138 

B.  Engraving  with  Partial  Covering 139 

C.  Electro-Engraving  Processes  140 

D.  Rieder's  Firs't  Investigations 141 

APPENDIX 149 


PREFACE 

While  giving  in  the  present  small  treatise  a  compilation  of  the 
published  information  in  the  field  of  the  manufacture  of  metallic 
articles  by  electrolytic  methods,  I  must  say  that  it  is  impossible  to 
treat  such  an  extensive  field  in  so  small  a  space  in  such  a  manner 
that  the  technician,  seeking  for  minute  details,  would  not  be  com- 
pelled to  seek  further  information  in  special  publications. 

The  material  can  only  be  handled  in  the  form  of  abstracts,  but 
in  many  cases  the  incompleteness  of  the  work  is  entirely  due  to 
the  fact  that  it  has  been  impossible  to  publish  all  the  secrets  of  the 
trade.  On  these  grounds  I  must  unfortunately  restrain  myself  in 
many  cases  from  presenting  such  important  data  as  to  the  profit- 
ableness of  most  of  the  processes ;  yet  in  many  cases  I  have  at- 
tempted to  supply  the  lack  of  such  data  by  my  own  calculations, 
where  the  firms  using  the  processes  were  unwilling  to  furnish 
such  data.  In  many  cases  profitableness  of  the  processes  may  be 
deduced  from  the  data  concerning  the  process,  which  have  been 
given. 

Many  of  the  processes  meet  with  a  great  many  unforseen  diffi- 
culties, such  as  in  the  details  of  apparatus  or  of  technical  practi- 
cability ;  many  on  the  contrary  cost  more  than  the  old  processes. 

The  thoughtful  artisan,  however,  will  find  much  food  for  re- 
flection in  many  of  the  processes  described,  and  be  induced  to  ex- 
periment further  in  one  or  another  direction,  or  to  attempt  to  per- 
fect some  of  these  processes,  and  I  will  consider  my  task  suffi- 
ciently completed  if  I  have  furnished  the  impulse  to  this  work  by 
my  modest  efforts. 

VIENNA.  W.  PFANHAUSER. 


I.    HISTORICAL  REVIEW. 


INTRODUCTION. 

M.  H.  Jakobi  is  generally  acknowledged  as  the  founder  of  gal- 
vanoplastic  reproduction  and  the  industrial  development  of  cop- 
per precipitation  resulting  therefrom.  He  first  presented  the  re- 
sults of  his  pioneer  work  to  the  St.  Petersburg  Academy  of  Sci- 
ences in  1838.  However,  Jordan  and  Spencer  contested  the 
priority,  but  it  has  been  proven  that  these  brought  their  experi- 
ments to  a  practical  stage  later  than  Jakobi.  Jakobi  also,  like  all 
workers  in  galvanoplasty  up  until  the  last  thirty  years,  worked 
with  the  well-known  cell  apparatus,  which  in  principle  was  prac- 
tically a  short-circuited  Daniell  cell. 

In  the  year  1840  Murray  introduced  the  graphitizing  of  non- 
conducting surfaces  and  in  1842  reproduced  the  first  engraved 
copper  plates  by  galvanoplastic  methods. 

ADVANCES  IN  THE  ART. 

The  manufacture  of  useful  articles  in  the  electrolytic  way  could 
naturally  only  become  practicable  with  the  advent  of  the  modern 
dynamo  machine  which  thus  makes  available  large  quantities  of 
electrical  energy.  With  the  increased  interest  in  all  such  pro- 
cesses \vhich  used  electricity  there  was  a  great  increase  along  ex- 
perimental lines,  towards  the  bringing  of  electricity  to  the  service 
of  the  metal  worker,  and  thus  the  circle  of  application  rapidly 
widened. 

As  in  almost  all  branches  of  electrochemistry,  so  here,  detailed 
information  of  processes,  such  as  is  used  by  technicians  for  their 
exact  reproduction,  are  seldom  to  be  had,  and  I  must,  in  many 
cases,  limit  myself  to  assumptions,  especially  where  calculations 
are  involved. 

At  the  present  time  there  are  a  large  number  of  more  or  less 
technically  available  processes,  widely  divergent  electrolytically, 
for  the  manufacture  of  useful  articles,  in  which  in  general  copper 
is  used  as  the  depositing  metal ;  and  it  is  only  very  recently  that 


2  MANUFACTURE  OF  METALLIC  OBJECTS 

nickel  has  become  of  importance,  unfortunately  only  to  a  limited 
extent,  because  in  the  case  of  nickel  quite  serious  difficulties  are 
encountered  which  limit  the  availability  of  this  otherwise  so  suit- 
able metal. 

It  can  be  said  of  some  of  the  processes  already  developed  that 
they  are  competing  successively  with  the  older  mechanical  ones 
and  many  of  them  will  drive  out  the  older  processes  as  soon  as  the 
small  difficulties  which  stand  in  the  way  of  their  technical  applica- 
tion have  been  overcome  by  the  general  advance  of  the  art. 

Nevertheless,  electrolysis  has  open  before  it  a  large  and  profita- 
ble field  in  galvano-technics,  when  cheap  power  and  raw  mate- 
rials are  brought  into  combination  with  well  organized  processes 
run  on  a  large  scale. 


II.    BATHS  FOR  COPPER  GALVANOPLASTY. 


The  most  important  galvanic  bath  technically  is  the  copper 
bath.  As  the  oldest  and  therefore  the  best  known  bath  it  has  been 
the  most  thoroughly  investigated,  and  for  this  reason  copper  has 
played  the  main  role  in  the  manufacture  of  articles  electrolyti- 
cally. 

NEUTRAL  BATH. 

It  has  been  found  that  when  electrolyzing  a  neutral  solution  of 
copper  sulphate,  CuSO4,  (obtained  by  boiling  it  with  copper  car- 
bonate, CuCO3,  and  subsequent  filtration)  there  always  results 
brittle  copper,  which,  in  being  lifted  off  the  cathode,  falls  in 
pieces.  After  continued  use  of  the  bath,  particularly  when  em- 
ploying high  current  densities,  the  character  of  the  precipitate  im- 
proves so  that  finally  perfectly  flexible  homogeneous  metal  is  ob- 
tained. The  explanation  of  the  above  described  facts  appears  to 
be  found  in  the  assumption  that  in  the  neutral  solution  there  is  a 
small  quantity  of  basic  sulphate  together  with  the  normal  salt, 
which  then  furnishes  traces  of  cuprous  oxide  during  the  electroly- 
sis ;  or  that  the  latter  is  formed  by  reaction  upon  the  already  pre- 
cipitated copper.  According  to  this  explanation  the  brittleness  of 
the  deposited  copper  is  explained  by  its  content  of  cuprous  oxide. 

WORK, OF  CHASSY,  1894. 

Chassy"1  furnishes  some  interesting  contributions  on  this  sub- 
ject. This  investigator  found  out  that  using  a  cathode  current 
density  of  I  ampere  per  square  decimeter  and  electrolyzing  a  sat- 
urated copper  sulphate  solution  at  100°  C.,  there  was  obtained  a 
red  precipitate  tarnishing  a  peculiar  blue,  and  consisting  of  small 
red  cubic  and  octahedral  crystals  of  cuprous  oxide,  Cu2O.  At 
temperatures  below  100°  C.  much  copper  appears  in  place  of  cup- 
rous oxide ;  at  40°  C.  and  thereunder  only  the  metal  is  precipi- 
tated. Similar  results  were  obtained  by  Chassy  by  decreasing  the 
concentration  or  the  current  density. 

1  Comptes  rendus,  1894,  119,  Vols.  4-5.  271. 


4  MANUFACTURE  OF  METALLIC  OBJECTS 

FOERSTER'S  WORK  ON  QUANTITATIVE  PRECIPITATION  OF 

COPPER. 

Very  soon  after  this  Dr.  F.  Foerster  published  his  interesting 
communication  upon  the  phenomena  of  the  electrolysis  of  copper 
sulphate  solutions,  which  he  brought  out  in  connection  with  his 
studies  upon  the  copper  voltameter.  Foerster  set  forth  the  follow- 
ing fundamental  laws  i1 

1.  With  current  densities  under  o.oi  ampere  per  square  deci- 
meter the  action  of  the  current  upon  the  concentrated  copper  sul- 
phate solution  at  the  ordinary  temperature  consists  in  a  liberation 
of  cuprous  ions  at  the  cathode.    With  increasing  current  densities 
more  and  more  cupric  ions  are  completely  discharged  and  rela- 
tively fewer  cuprous  ions  produced  by  the  current,  without,  how- 
ever, the  production  of  the  latter  completely  ceasing  even  at  high 
current  densities. 

2.  The  tendency  of  the  cupric  ions  of  the  sulphate  solution  to 
pass  over  into  cuprous  ions  increases  very  markedly  with  the  tem- 
perature so  that  at  100°  C.  the  current  produces  almost  exclusive- 
ly cuprous  ions  at  the  cathode,  even  with  current  densities  of  0.03 
ampere  per  square  decimeter  in  a  concentrated  copper  sulphate 
solution. 

3.  The  production  of  cuprous  ions  can  take  place  in  copper  sul- 
phate solutions  without  the  influence  of  the  current,  as  in  cupric 
chloride  solutions,  by  the  action  of  metallic  copper  upon  the  cup- 
ric ions  of  the  cupric  sulphate  solution : 

++  + 

Cu  +  Cu  =  2Cur 

This  action  proceeds  until  the  cupric  sulphate  solution  is  satu- 
rated with  cuprous  sulphate.  It  is  difficult  to  determine  in  the 
case  of  copper  sulphate  solutions  to  what  extent  the  formation  of 
cuprous  sulphate  depends  upon  this  solution  of  copper  or  upon 
pure  electrolytic  action ;  Foerster  thinks  the  latter  to  be  the  simp- 
lest and  most  probable  factor. 

4.  Under  similar  conditions  more  cuprous  ions  will  be  formed 

1  Zeitschr.  f.  Elektrochemie  3,  480  and  481. 

2  This  fact  was  established  a  long  time  ago  by  Jakobi  (see   Wiedemann,  Zeitschr.   f. 
Elektrochemie  a,  510)  but  the  knowledge  of  it  apparently  had  no  influence  upon 
the  later  developments  of  the  subject. 


BATHS  FOR  COPPER  GAIA/ANOPLASTY  5 

in  a  sulphuric  acid  solution,  the  greater  the  concentration  of  the 
cupric  ions  present. 

5.  If  the  solution  is  neutral  the  cuprous  sulphate  produced  suf- 
fers hydrolysis  as  soon  as  its  concentration  has  exceeded  a  certain 
limiting  value.    The  equation  of  the  change  is 

2Cu  4-  SO4  +  H2O  =  Cu,O  +  2H  H-  SO4. 

By  reason  of  this  reaction  cuprous  oxide  is  often  separated 
upon  the  cathode  in  crystals  having  an  adamantine  lustre,  leaving 
in  solution  free  sulphuric  acid. 

6.  If  the  solution  is  sufficiently  acid  no  hydrolysis  will  take 
place  and  much  larger  quantities  of  cuprous  ions  will  remain  in 
solution  than  if  the  latter  is  neutral. 

Even  in  this  case,  however,  there  is  a  limit  to  the  enrichment  of 
the  solution  in  cuprous  salt,  for  as  soon  as  the  relative  concen- 
tration of  the  cuprous  ions  to  the  cupric  ions  has  passed  a  certain 
limit  the  former  change  back  to  cupric  ions  thereby  separating  out 
metallic  copper : 

+        +  + 
2Cu  =  Co  +  Cu. 

Referring  back  to  the  phenomenon  of  solution  described  in 
paragraph  3,  we  see  that  we  have  a  reversible  reaction 

+  +  + 

Cu  -f  Cut^  2Cu. 

7.  There  results  at  the  cathode  metallic  copper  by  the  above  de- 
scribed operations  from  very  acid  cupric  sulphate  solutions,  also 
when  the  current  density  only  produces  cuprous  ions. 

In  the  latter  case  the  copper  might  be  regarded  as  separated  out 
""secondarily"  and  does  not  form  uniform  deposits  like  the  copper 
separated  out  in  the  ordinary  way  from  acid  solutions,  but  ap- 
pears in  small  single,  distributed  crystals. 

8.  If  the  cuprous  ions  get  to  the  anode  they  again  take  up  posi- 
tive charges  and  are  converted  into  cupric  ions ;  the  current  is 
then  doing  at  the  anode,  in  a  measure  as  this  reaction  takes  place, 
other  work  than  ionizing  the  anode  itself. 

As  is  seen  from  the  preceding  paragraphs  the  current  density 
used  plays  an  extraordinarily  important  part  even  in  the  correct 
solution,  no  less  than  the  content  of  acid  and  the  temperature  of 


6  MANUFACTURE  OF  METALLIC  OBJECTS 

the  solution.  The  avoidance  of  the  formation  of  cuprous  ions  is 
a  fundamental  condition  for  quantitative  precipitation  of  copper 
and  likewise  for  the  obtaining  of  coherent  metal. 

Foerster  found  the  results  collected  together  in  the  following 
table  when  electrolyzing  acid  and  neutral  cupric  sulphate  solutions 
of  various  concentrations  with  various  current  densities. 

Amp  per. 
CuSO4.  H2SO4.          sq.  dm.  Properties  of  the  Cathode  copper. 

2.0  13.0  At  places  powdery 

2.0  10.0  Dense,  bright  red 

l.o  i  7.0  Powder}' 

i.o  i  4.0  Strongly  adherent,  bright  red 

0.25  i.o  Dark  red,  powdery 

0.25  0.7  Beautiful,  bright  red 

0.25  I  1.8  Dark  red,  powdery 

0.5  0.3  Ditto 

0.5  0.15  Bright  red  adherent 

In  this  table  the  numbers  under  the  headings  CuSO4  and 
H2SO4  denote  the  number  of  gram-equivalents  of  these  materials 
present  in  one  litre  of  the  electrolyte  (by  weight  the  gram-equiv- 
alents are  80  and  49  respectively). 

Foerster  worked  wtih  -stationary  electrolytes  and  the  above 
values  are  valid  only  for  such. 

As  early  as  1857  Magnus1  published  a  work  upon  "Limiting" 
Values  of  the  Current  Density  in  Copper  Sulphate  Solutions," 
and  here  we  may  also  refer  to  the  work  of  Karl  Ullmann,  who  re- 
ported upon  the  influence  of  time  upon  the  phenomena  at  the 
cathode  in  the  electrolysis  of  copper  sulphate  solutions.  It.  would 
lead  us  too  far  to  reproduce  at  length  Ullmann's  results,  and  I 
content  myself  with  referring  to  his  very  interesting  original  man- 
uscript.2 

STUDIES  BY  HUBL,  1886. 

Arthur  von  Hiibl  described  in  1886  in  the  "Mitteilungen  des  k. 
u.  k.  militar-  geographischen  Institutes,"  6,  51  to  96,  his  funda- 
mental studies  upon  the  properties  of  electrolytically  precipitated 
copper,  and  I  extract  freely  from  this  communication  because  the 
physical  properties  of  cathode  copper  are  treated  with  particular 
completeness  and  thus  must  be  of  special  interest  to  us.  Hiibl 
writes : 

1  Pogg.  Ann.  102,  (1857)  i  to  54. 

2  Zeitschr.  f.  Elektrochemie,  3,  516  et  seq. 


BATHS  FOR  COPPER  GALVANOPLASTY  7 

"If  an  addition  of  sulphuric  acid  is  made  to  the  copper  sulphate 
•solution  then  both  copper  sulphate  and  sulphuric  acid  take  part 
in  carrying  the  current  and  both  will  be  decomposed  in  quantity 
corresponding  to  their  conductivities.1  Since  the  sulphuric  acid 
is  very  strongly  dissociated  in  comparison  to  the  copper  sulphate 
and  therefore  is  an  excellent  conductor,  the  addition  of  only  a 
few  per  cent,  of  acid  results  in  the  conducting  of  the  current  being 
done  practically  by  the  acid  itself.  The  separating  out  of  copper 

+ 
at  the  cathode  proceeds  as  follows :  that  H  precipitates  copper 

secondarily  because  of  its  higher  discharge  potential,  while  cop- 
per is  precipitated  primarily  only  in  quantity  corresponding  to  the 
dissociated  fraction  of  copper  sulphate  present. 

"If  the  hydrogen  finds  at  its  point  of  evolution  an  insufficient 
quantity  of  copper  in  the  solution,  that  is  if  the  solution  is  too 
dilute  in  comparison  with  the  quantity  of  hydrogen  produced, 
then  the  latter  separates  out  as  free  gas  and  results  in  a  loosely 
coherent  deposit  of  copper.  This  phenomenon  is  therefore  to  be 
observed ;  the  lower  the  current  density  the  more  dilute  the  solu- 
tion in  copper  sulphate  and  the  greater  the  addition  of  sulphuric 
acid.  The  beginning  of  the  separation  of  hydrogen  is  character- 
ized very  plainly  by  the  development  of  a  strong  polarization  by 
which  the  apparent  resistance  of  the  electrolyte  suffers  a  sudden 
Increase. 

The  Separation  of  Copper  in  Granular  Form. 
"If  the  quantity  of  hydrogen  separating  out  is  small  in  propor- 
tion to  that  of  the  copper  no  evolution  of  gas  takes  place  at  the 
cathode:  the  hydrogen  apparently  combines  with  the  copper, 
forming  a  hydride,  which  combined  with  the  pure  metal  forms 
a  non-homegeneous,  powdery,  spongy  or  sandy  precipitate  of 
more  or  less  dark  color.  Only  on  further  increase  of  the  current 
density,  does  the  quantity  of  hydrogen  set  free  become  so  great 
that  it  appears  in  the  form  of  gas  bubbles. 

Changes  in  Concentration  During  Electrolysis. 
"If  the  concentration  of  the  bath  is  investigated  during  the  elec- 
trolysis at  different  places  it  is  found  to  vary  and  it  may  be  easily 

1  This  explanation  is  no  longer  considered  valid. — Translator. 


8  MANUFACTURE  OF  METALLIC  OBJECTS 

proven  that  a  dilution  takes  place  at  the  negative  pole,  and  at  the 
positive  pole  a  concentration  of  the  solution.  In  the  presence  of 
free  sulphuric  acid  the  dilute  solution  at  the  cathode  will  be  richer 
in  acid  than  the  concentrated  solution  at  the  anode.  Hittorf  ex- 
plains these  changes  in  concentration,  by  the  assumption  that  the 
ions  move  with  different  velocities  towards  the  electrodes  (Wiede- 
mann,  Elektrizitat  2,  548,  942),  while  the  increase  of  acid  at  the 
cathode  is  produced  by  the  indirect  precipitation  of  copper  by  hy- 
drogen. 

"The  concentrated  solution  is  specifically  heavier,  the  dilute 
solution  lighter  than  the  original,  and  therefore  when  the  elec- 
trodes hang  vertical  a  current  of  electrolyte  rises  upwards  around 
the  cathode  and  flows  downwards  around  the  anode.  The  conse- 
quence of  this  phenomenon  is  that  after  some  time  a  layer  of  very 
concentrated  solution  is  found  at  the  bottom  of  the  vessel  while  at 
the  surface  a  very  dilute  solution  and  finally  only  an  acid  solution 
is  to  be  found. 

"These  facts  entail  many  disadvantages  in  practice  and  have  to 
be  very  carefully  watched  when  working  with  vertical  electrodes 
and  are  the  more  in  evidence  the  greater  the  current  density  and 
the  extent  of  the  depositing  surfaces. 

Inequalities  in  the  Copper  Precipitate. 

"The  current  of  solution  rising  at  the  cathode  is  divided  quick- 
ly into  single  vertical  rising  parts  by  the  small  irregularities  found 
upon  the  cathode  surface,  and  since  these  divided  currents  vary 
in  their  concentration  they  produce  an  unequal  distribution  of  the 
current  passing  to  the  cathode.  There  will  be  therefore  formed 
vertical  lines  upon  the  cathode  with  gutter-like  grooves  in  be- 
tween ;  the  lines  grow  rapidly  and  therefore  increase  the  difficul- 
ty both  in  consequence  of  increasing  the  differences  in  concentra- 
tion, as  also  because  the  projecting  lines  receive  more  copper  de- 
posit than  the  grooves  between  them. 

"A  further  consequence  of  these  currents  is  that  the  copper 
crystals  of  which  every  galvanic  deposit  consists  arrange  them- 
selves in  certain  directions  and  thereby  make  the  cohesive  strength 
of  the  precipitate  different  in  different  directions. 

"The  layers  of  liquid  produced  in  time  cause  the  heavy  solu- 


BATHS  FOR  COPPER  GALVANOPLASTY  9 

tions  at  the  bottom  of  the  vessel  bathing  the  lower  end  of  the 
-anode  to  cover  it  with  copper  sulphate  crystals,  which,  being  poor 
conductors  of  electricity,  introduce  resistance.  On  the  other  hand 
the  different  conductivity  of  the  concentrated  and  dilute  solutions 
produce  an  unequal  division  of  the  current,  so  that  finally  the  di- 
lute or  simple  acid  solution  on  the  surface  may  produce  a  deposit 
of  non-homogeneous  copper.  For  this  reason  it  will  always  be  ob- 
served that  the  lowest  lying  part  of  the  cathode  grows  faster  than 
those  parts  which  are  nearer  the  surface  and  that  the  first  indica- 
tion of  the  production  of  hydrogen,  namely  the  precipitation  of 
sandy  copper,  occurs  first  in  the  upper  part  of  the  electrolyte. 

"In  order  to  get  a  better  picture  of  the  stratification  of  the  solu- 
tion, tests  were  taken  at  different  depths  through  a  bath  contain- 
ing 19  per  cent,  of  copper  sulphate  and  3^2  per  cent,  of  sulphuric 
acid,  during  the  course  of  the  electrolysis.  The  size  of  the  elec- 
trodes was  about  50  centimeters  square,  the  distance  apart,  8  cen- 
timeters, and  the  current  strength  40  amperes.  After  running  7 
Tiours  three  tests  taken  from  between  the  electrodes  showed  the 
following  composition : 

1.  Test  from  the  surface:     12.7  per  cent,  copper  sulphate,  3.9 
per  cent,  sulphuric  acid. 

2.  Test  25  centimeters  under  the  surface:    21  per  cent,  copper 
sulphate,  3.4  per  cent,  sulphuric  acid. 

3.  Test  50  centimeters  under  the  surface :     29.2  per  cent,  cop- 
per sulphate,  3  per  cent,  sulphuric  acid. 

Concentration  Currents. 

"A  further  evil  of  the  stratification  of  the  liquid  is  observed  if, 
after  shutting  off  the  current,  the  electrodes  are  allowed  to  stand 
in  the  bath  by  themselves  for  several  hours.  The  copper  dipping 
into  the  two  solutions  of  different  concentration  causes  concentra- 
tion currents  which  pass  from  the  metal  in  the  dilute  acid  solu- 
tion above,  through  the  liquid  to  the  concentrated  solution  below 
and  to  the  end  of  the  electrode  in  contact  with  it,  and  produce 
solution  of  the  upper  part  of  the  electrode  and  deposition  upon  the 
lower  part. 

"The  existence  of  currents  of  this  kind  was  first  observed  by 
Buchholz  (Gehlens,  Journal  de  Chemie  5,  1808).  The  upper  part 


IO  MANUFACTURE  OF  METALLIC  OBJECTS 

of  the  cathode  of  precipitated  copper  being  in  dilute  acid  solution,. 
behaves  after  the  interruption  of  the  current  exactly  like  an 

anode ;  its  surface  is  dissolved  by  SO4.  As  will  be  later  explain- 
ed at  length,  there  forms,  however,  on  the  surface  of  each  anode 
a  loosely  coherent  dark  colored  deposit  which,  when  electrolysis 
is  resumed  after  an  interruption,  prevents  the  newly  precipitated 
metal  from  uniting  perfectly  with  that  earlier  precipitated.  In- 
consequence of  this  phenomenon  which  repeats  itself  at  each  in- 
terruption of  the  current,  the  copper  precipitated  may  consist  of 
several  loosely  coherent  layers. 

"All  the  difficulties  which  are  met  with  in  practice  in  conse- 
quence of  the  inequalities  in  the  solution  may  be  overcome  in  two 
simple  ways :  through  a  mechanical  arrangement  for  a  continual 
mixing  of  the  bath  or  by  arranging  the  electrodes  horizontally. 

Maximum  Current  Density. 

"As  has  already  been  mentioned,  there  is  formed  during  elec- 
trolysis, if  a  certain  current  density  is  exceeded,  a  non-coherent 
precipitate  caused  by  the  free  development  of  hydrogen.  This  is 
very  evidently  perfectly  useless  for  practical  purposes.  But  since 
it  is  on  the  other  hand  very  desirable  to  hasten  the  galvanoplastic 
processes  as  much  as  possible  it  is  necessary  to  make  use  of  higher 
current  densities.  It  is  therefore  of  the  greatest  value  to  know 
this  maximum  current  density  which  may  be  used  in  those  baths 
of  different  composition,  and  still  produce  with  certainty  fault- 
less, strong  and  flexible  precipitates. 

"The  results  of  experiments  in  this  direction  are  contained  in 
the  following  table  which  gives  the  current  densities  at  which  fre/e 
hydrogen  is  evolved,  immediately  upon  the  closing  of  the  circuit. 
This  is  evidenced  both  by  the  occurrence  of  the  already  describ- 
ed polarization  as  well  as  by  the  occurrence  of  non-homogeneous 
dark  metallic  deposits. 

Concentration  of       Current  density  at  which  the  evolution  of  hydrogen  begins,  in 

~~'n,are  decimetre. 

3.0  #  H2S04.  6.0  #  H£SO4. 

0.68 

1.44  1.40 

3.40  3.20 

5.72  4.60 

7.08  6. co 


the  solution  in 

amperes  pe 

CuS04 

Per  cent. 

Normal. 

0.6  $  HSSO<. 

I.o 

0.32 

.... 

2-5 

1.20 

080 

5-0 

2.60 

1.  60 

10.  0 

5-12 

.... 

15.0 

7.80 



20.0 

10.20 

.... 

BATHS  FOR  COPPER  GALVANOPLASTY  II 

"From  this  table  it  is  to  be  concluded  that : 

1.  The  allowable  current  densities  are  approximately  propor- 
tional to  the  concentration  of  the  solution. 

2.  A  very  small  addition  of  sulphuric  acid  lowers  very  much 
the  allowable  current  density,  while  a  further  addition  of  acid  ex- 
ercises a  relatively  small  influence.     This  fact  is  explained  very 
simply  by  the  relatively  higher  conductivity  of  the  sulphuric  acid. 
If  to  a  20  per  cent,  solution  of  copper  sulphate,  I  per  cent,  of  sul- 
phuric acid  is  added  it  will  share  to  an  equal  extent  in  the  con- 
duction of  the  current ;  while  with  5  per  cent,  of  sulphuric  acid 
the  acid  does  practically  all  the  current  conducting.     It  the  last 
case  almost  all  the  copper  precipitated  is  separated  out  second- 
arily :  therefore,  a  still  further  addition  of  sulphuric  acid  must  be 
almost  without  influence. 

"In  practical  galvanoplasty  a  number  of  conditions  arise,  how- 
ever, which  influence  very  unfavorably  the  current  densities 
which  can  be  used  in  practice. 

"To  start  with,  it  must  be  observed  that  the  solution  at  the 
negative  electrode  and  at  the  surface  of  the  bath  becomes  poorer 
in  copper ;  and  that,  therefore,  the  development  of  free  hydrogen 
may  occur  often  when  using  current  densities  below  the  normal 
maximum  value,  if  the  copper  content  of  the  layer  of  liquid  be- 
comes so  decreased  by  electrolysis  that  it  no  longer  suffices  to 
furnish  copper  in  exchange  for  hydrogen.  In  consequence  of  this 
condition  it  is  scarcely  possible  in  practice  to  use  more  than  one- 
half,  usually  only  one-third,  of  the  above  given  values  of  current 
•densities.  If,  however,  active  circulation  of  the  fluid  is  provided 
for,  so  that  the  negative  electrode  is  continually  supplied  with  new 
copper  sulphate  solution,  faultless  precipitates  will  be  obtained  up 
to  the  maximum  values  given.  With  very  energetic  agitation  of 
the  solution  even  these  numbers  can  be  greatly  exceeded,  since 
investigations  on  a  small  scale  have  shown  that  with  these  condi- 
tions a  one  per  cent,  neutral  bath  may  be  worked  with  0.8  am- 
pere, a  20  per  cent,  solution  with  18  amperes  current  density  and 
still  give  practically  useful  deposits.  From  practical  considera- 
tions, however,  only  a  very  gentle  agitation  of  the  bath  is  possi- 
'ble,  in  which  case  the  use  of  one-half  to  two-thirds  of  the  maxi- 
mum density  named  appears  to  be  all  that  is  allowable. 


12  MANUFACTURE  OF  METALLIC  OBJECTS 

"From  these  remarks  it  appears  that  the  highest  current  den- 
sity practicable  in  galvanoplastic  practice  is  between  the  following 
limits. 

Maximum  current 
density  practicably  al- 
lowable for  solutions  in 

Composition  of  the  bath.  amperes      per     square 

decimeter. 

In  gentle 

At  rest.       motion. 

amperes,    amperes. 

r5%  copper  sulphate,  neutral 2.6-3.9  3-9-5-2 

15%  copper  sulphate  -f-  6%  sulphuric  acid 1.5-2.3  2.3-3.0 

20%  copper  sulphate,  neutral 3.4-5.1  5.1-6.8 

20%  copper  sulphate  -f  6%  sulphuric  acid 2.0-3.0  3.0-4.0 

"The  current  density  could  be  still  further  increased  if  it  were 
possible  to  use  a  more  concentrated  copper  solution,  which,  how- 
ever, is  not  practicable  when  using  copper  sulphate  because  on  the 
one  hand  the  solubility  of  this  salt  is  very  noticeably  diminished 
by  the  addition  of  the  necessary  sulphuric  acid,  and  because  on 
the  other  hand  the  concentration  of  the  liquid  layer  around  the 
anode  increases  during  the  electrolysis  and  yet  must  always  pos- 
sess the  capability  of  dissolving  the  newly  formed  sulphate. 

Solubility  of  Copper  Sulphate. 

"The  solubility  of  copper  sulphate  in  dilute  sulphuric  acid  of 
different  concentrations  has  been  determined  experimentally  at 
55°  C.  and  gave  the  following  results: 

In  the  presence  of  o%  H2SO4  i  liter  of  saturated  solution  contains  39 
gms.  CuSo4. 

In  the  presence  of  i  %  H2SO4  i  liter  of  saturated  solution  contains  348 
gms.  CuSO4. 

In  the  presence  of  2%  H2SO4  i  liter  of  saturated  solution  contains  308 
gms  CuSO4. 

In  the  presence  of  $%  H2SO4  i  liter  of  saturated  solution  contains  280 
gms.  CuSO4. 

In  the  presence  of  4%  H2SO4  i  liter  of  saturated  solution  contains  260 
gms.  CuSO4. 

In  the  presence  of  5$  H2SO4  i  liter  of  saturated  solution  contains  253 
gms.  CuSO4. 

In  the  presence  of  6%  H2SO4  i  liter  of  saturated  solution  contains  245 
gms.  CuSO4. 

In  the  presence  of  8^  H.2SO4  i  liter  of  saturated  solution  contains  231 
gms.  CuSO4. 


ft 

BATHS  FOR  COPPER  GALVANOPI^ASTY  13 

In  the  presence  of  10%  H2SO4  i  liter  of  saturated  solution  contains  215 
gms.  CuSO4. 

In  the  presence  of  12%  H2SO4  I  liter  of  saturated  solution  contains  197 
gnis.  CuSO4. 

In  the  presence  of  14%  H2SO4  i  liter  of  saturated  solution  contains  180 
gms.  CuSO4. 

"It  is  to  be  seen  from  these  figures  that  in  the  presence  of  4  per 
cent,  of  sulphuric  acid  not  more  than  26  per  cent,  of  copper  sul- 
phate can  be  dissolved,  and  therefore  a  solution  of  this  concentra- 
tion can  no  longer  be  used.  For  a  gently  agitated  bath  a  solution 
containing,  at  the  highest,  20  per  cent,  may  be  used ;  but  in  a  bath 
not  stirred  separation  of  crystals  on  the  anode  will  begin  even  at 
this  concentration  if  the  highest  curent  densities  are  used  and  4 
per  cent,  of  sulphuric  acid  is  present.  It  is  finally  self-evident 
that  the  temperature  of  the  bath  may  also  exert  an  important  in- 
fluence upon  the  above  described  conditions  and  under  some  cir- 
cumstances may  also  be  the  determining  factor  of  the  allowable 
current  density. 


III.    PHYSICAL  PROPERTIES  OF  THE  COPPER 

DEPOSIT. 


The  endeavor  of  galvanoplastics  must  be  to  produce  a  copper 
deposit  with  properties  suitable  for  the  purpose  desired, — that  is, 
with  certain  definite  physical  properties.  Since  these  properties 
must  be  within  certain  limits,  it  is  necessary  to  know  those  factors 
which  determine  the  qualities  of  the  deposits  obtained. 

INFLUENCE  OF  FOREIGN  ADMIXTURES. 

The  views  on  this  subject  are  contradictory.  This  is  explained 
by  the  great  difficulties  which  are  experienced  in  carrying  out 
such  investigations.  The  properties  of  the  deposit  are  without 
doubt  often  very  largely  influenced  by  secondary  processes  con- 
nected with  changes  or  small  impurities  in  the  bath,  and  it  is  often 
impossible  to  recognize  and  trace  out  to  their  limit  the  phenomena 
in  question.  If  we  take  into  consideration  the  changes  which  cop- 
per, like  other  metals,  undergoes  through  the  presence  of  traces  of 
foreign  bodies,  for  instance  even  by  cuprous  or  cupric  oxide,  there 
can  be  no  doubt  that  similar  considerations  must  be  of  an  import- 
ant influence  upon  the  properties  of  the  galvanic  deposit.  There 
is  no  doubt  ,of  this  in  the  case  of  deposits  gotten  from  the  acetate 
or  from  cupric  chloride,  as  also  from  basic  copper  solutions. 

STRUCTURE. 

Aside  from  the  secondary  processes  taking  place  and  the  influ- 
ence of  impurities  in  the  bath,  the  physical  properties  of  the  cop- 
per are  considerably  influenced  by  the  structure  of  the  same. 
The  structure  is  crystalline  but  the  single  crystals  are  more  or  less 
developeed.  This  consideration  as  well  as  their  orientation  must 
determine  largely  the  strength,  elasticity  and  hardness,  etc.,  of  the 
metal. 

Since  the  metal  is  separated  from  a  copper  solution  by  the  elec- 
tric current,  the  structure  of  the  crystalline  aggregate  must  be 
determined  by  two  factors ;  composition  of  the  bath,  and  current 
strength. 


PHYSICAL    PROPERTIES    OF   COPPER   DEPOSITS  15 

Two  views  have  been  advanced  respecting  the  influence  of  these 
two  factors.  One  was  advanced  by  Smee  and  is  summed  up  in  the 
statement:  current  density  and  concentration  of  the  bath  deter- 
mine by  their  relative  proportions  the  quality  of  the  metal.  The 
second  view  was  given  by  F.  Kick  as  follows :  the  quality  of  the 
galvanic  deposit  is  dependent  upon  the  composition  of  the  elec- 
trolyte and  independent  of  the  current  density. 

Smee,  upon  the  basis  of  his  numerous  investigations,  comes  to 
the  following  conclusions : 

1.  The   metal   is   separated   out   in   a   non-homogeneous   form 
(powdery,  spongy,  or  sandy)  if  the  current  strength  is  so  great 
that  evolution  of  hydrogen  occurs  simultaneously  with  the  deposi- 
tion of  the  metal. 

2.  The  metal  is  separated  out  in  a  coarsely  crystalline  form  if 
the  current  strength  is  far  from  being  sufficient  to  cause  evolu- 
tion of  hydrogen. 

3.  The  metal  appears  as  a  tough,  solid,  fine-grained  deposit  if 
the  current  strength  is  as  great  as  possible,  but  not  strong  enough 
to  cause  evolution  of  hydrogen. 

Smee  therefore  concludes  that  by  the  application  of  proper  cur- 
rent density  it  is  possible  to  obtain  deposits  having  certain  proper- 
ties from  baths  of  almost  any  concentration. 

H.  Meidinger  (Dingier  p.  J.  218,  219)  reviews  the  conclusion 
of  Smee  and  adds  this  statement:  "The  relation  of  the  current 
density  to  the  concentration  of  the  solution  is  a  constant  for  a 
determined  quality  of  the  precipitate,  but  the  limits  are  not  very 
sharply  defined.  If  a  deposit  of  certain  properties  is  obtained 
from  a  concentrated  bath  a  similar  precipitate  might  be  obtained 
from  a  bath  of  half  the  concentration  by  half  the  current  strength, 
from  a  bath  of  one-third  the  concentration  by  one-third  the  cur- 
rent strength,  etc." 

Hiibl  made  extensive  experiments  to  find  the  most  suitable  re- 
lations for  producing  the  best  precipitates.  His  preliminary  ex- 
periments on  a  small  scale,  to  determine  the  appearance  and  the 
brittleness  of  the  precipitates,  were  carried  out  as  follows : 

HUBL'S  INVESTIGATIONS. 

The  copper  sheets  used  as  electrodes  were  50  mm.  wide,  100 


M    . 
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UNIVERSITY 


PHYSICAL,    PROPERTIES    OI?    COPPER   DEPOSITS  17 

-mm.  long  and  held  at  a  distance  of  20  mm.  apart  by  suitable  sup- 
ports. The  cathode  was  silvered  and  slightly  iodized  in  order  to 
facilitate  loosening  of  the  precipitate.  A  glass  beaker  rilled  with 
"the  experimental  solution  was  brought  under  the  electrodes  and 
raised  until  the  latter  dipped  50  mm.  into  the  solution.  Daniell  or 
Bunsen  cells  served  as  the  source  of  current,  a  circular  rheostat 
in  the  circuit  serving  to  regulate  the  current  strength.  When  ex- 
periments were  to  be  made  with  agitated  baths  the  desired  agita- 
tion was  obtained  by  the  bubbling  in  of  air. 

Two  pairs  of  electrodes  were  always  in  the  circuit,  one  pair 
dipping  into  a  5  per  cent.,  the  other  into  a  20  per  cent.,  solution 
of  copper  sulphate. 

At  first  so-called  neutral  solutions  (boiled  with  copper  carbon- 
ate) were  electrolyzed,  using  various  current  densities,  the  solu- 
tion being  replaced  after  each  experiment  in  order  to  produce  no 
"irregularity  by  the  change  in  the  composition  of  the  bath. 

NEUTRAL  SOLUTIONS. 

It  follows  from  these  results  that,  using  a  so-called  neutral  solu- 
tion and  a  smaller  current  density  in  a  5  per  cent,  bath,  better 
-precipitates  are  obtained  than  in  a  concentrated  solution,  while  the 
appearance  of  the  metal  in  both  cases  is  the  same.  The  cause  of 
this  phenomenon  has  already  been  alluded  to.  •  The  addition  of 
sulphuric  acid  hinders  the  formation  of  large  crystals.  There  are 
therefore  obtained  with  small  current  densities  very  finely  granu- 
lar, tough  deposits  whose  texture  and  behavior  in  bending  are  in- 
dependent of  the  concentration  of  the  solution. 

The  more  or  less  crystalline  texture  appears  as  well  with  so- 
called  neutral  as  with  acid  baths,  depending  entirely  upon  the  cur- 
rent strength  used.  The  coherence  of  the  metal  which  is  to  some 
extent  shown  by  its  behavior  on  bending  agrees  completely  with 
the  development  of  the  crystals  in  acid  baths,  but  in  neutral  solu- 
tions appears  to  be  determined  almost  entirely  by  the  basicity  of 
the  solution. 

In  order  to  obtain  a  useful  deposit  the  current  density  used 
should  not  exceed  a  maximum  already  stated,  as  determined  by 
the  concentration  of  the  bath  ;  within  this  limit,  however,  the  cur- 
rent density  is  the  only  determining  factor  of  the  texture  and  the 
properties  depending  upon  the  texture. 


l8  MANUFACTURE  OF  METALLIC  OBJECTS 

THE  ACTION  OF  ADDITIONS. 

The  reason  why  only  finely  crystalline  deposits  are  obtained' 
when  acid  is  added  has  so  far  not  been  explained.  Meidinger  at- 
tempted an  explanation,  according  to  which  the  cause  was  the  in- 
direct separation  of  the  metal,  but  in  this  case  similar  influences 
should  be  exerted  by  other  substances.  If  to  a  10  per  cent,  so- 
called  neutral  bath  there  is  added  10  per  cent,  of  sodiuin  sulphate, 
there  must  in  this  case  according  to  the  conductivity  of  the  latter, 
certainly  be  a  large  part  of  the  copper  separated  out  indirectly  by 
the  sodium.  But  with  a  current  density  of  0.8  of  an  ampere  such 
a  solution  gave  a  quite  as  coarsely  crystalline  and  fragile  deposit 
as  without  this  addition. 

ADDITION   OF  SULPHURIC  ACID. 

Concerning  the  quantity  of  the  sulphuric  acid  added,  experi- 
ments on  this  point  show  no  difference  in  the  texture  of  the  pre- 
cipitate when  2  to  8  per  cent,  of  acid  was  present. 

TENSILE  STRENGTH. 

The  determination  of  accurate  values  for  the  tensile  strength  of 
galvanoplastic  deposits  is  attended  with  extraordinary  difficulties 
and  in  spite  of  serious  attempts  it  was  not  found  possible  to  obtain 
complete  correspondence  between  the  numbers  found  and  the  var- 
iations in  the  method  of  producing  the  deposit. 

A  great  difficulty  is  primarily  in  the  production  of  perfectly 
faultless  plates  of  dimensions  large  enough  to  make  the  tests  on 
them.  Irregularities  in  the  growth  of  the  precipitate  (the  forma- 
tion of  copper  granulees  which  when  removed  show  a  changed 
structure  at  the  point  where  they  have  been  removed)  influences 
self-evidently  the  numbers  found  by  the  testing  machine. 

Experience  has,  however,  shown  that  copper  of  smaller 
strength  is  deposited  from  old  baths.  The  reason  of  this  phenom- 
enon could  not  be  explained,  since  the  chemical  analysis  of  the  old 
baths  with  the  exception  of  a  trace  of  cuprous  salt,  showed  no 
differences  from  the  new  baths  just  going  into  use.  It  appears 
highly  probable  that  the  turbidity  of  the  baths  which  have  been 
used,  caused  by  the  particles  of  anode  slime  in  suspension,  exert 
a  prejudicial  influence  on  the  precipitate.  It  is  also,  however,  very 


i  ' 

PHYSICAL   PROPERTIES   OF    COPPER   DEPOSITS  IQ 

probable  that  substances  coming  from  the  lining  material  of  the 
cell,  as  lacquer  upon  the  back  of  the  cathodes,  contaminate  the 
t>aths. 

For  this  reason  the  following  results,  which  have  been  taken 
from  copper  specimens  precipitated  from  long  used  baths,  do  not 
represent  the  best  obtainable  results  and  can  on  these  grounds 
only  be  regarded  as  values  for  comparison  among  each  other. 

The  method  of  the  production  of  the  specimens  was  as  follows : 
A  layer  of  copper  0.8  to  i  mm.  in  thickness  was  deposited  by  a 
carefully  measured  current  from  a  dynamo  machine,  upon  a 
smooth  silvered  copper  plate  of  proper  dimensions,  covered  on 
the  back  with  an  asphalt  varnish.  The  current  density  was  cal- 
culated from  the  current  strength  and  the  size  of  the  plates.  Two 
sheets  each  50  mm.  wide  were  cut  from  the  middle  of  the  plate  in 
a  determined  direction  and  subjected  to  a  tensile  test. 

TENSILE  STRENGTH  TESTS. 

The  table  in  the  appendix  contains  the  average  values  gathered 
from  two  series  of  investigations. 

Considering  first  the  values  for  each  test  obtained  from  baths 
of  similar  concentration,  the  following  conclusions  may  be  drawn : 

1.  The  absolute   strength   increases  with  the  current  density. 
With  not  quite  pure  baths  the  differences  are  smaller  than  when 
using  freshly  made  up  solutions.     The  relatively  highest  values 
appear  to  be  obtained  with  a  current  strength  of  2.2  to  3  amperes ; 
with  still  higher  densities  the  absolute  strength  decreases.    This  is 
explained  by  the  fact  that  4  amperes  is  in  the  neighborhood  of  the 
practically  allowable  current  density,  and  at  this  strength  the  ten- 
dency becomes   manifest   to   separate   out   sandy   copper.      This 
phenomenon  will  also  occur  in  a  short  time  if  the  agitation  of  the 
"bath  is  ceased  and  it  is  allowed  to  stand  quiet. 

2.  The  elastic  limit  and  elongation  show  a  maximum  with  cur- 
rent strengths  of  i.o  to  1.5  amperes. 

3.  The  toughness  of  the  metal,  represented  by  the  elongation  at 
rupture,  decreases  with  increase  of  current  strength. 

The  maximum  value  lies  below  a  density  of  0.6  ampere,  yet 
it  might  be  supposed  that  with  very  small  densities  the  toughness 
would  decrease  because  of  the  appearance  of  a  more  crystalline 
structure. 


2O  MANUFACTURE  OF  METALLIC  OBJECTS 

4.  The  hardness  increases  with  the  current  density.  It  is  to  be- 
observed  that  the  method  of  determining  hardness  gives  correct 
results  with  thick  plates,  but  that  with  thin  sheets  deformation 
may  occur,  making  the  method  of  the  determining  of  the  hardness 
unreliable. 

Discussing  the  relations  between  the  above  properties  and  the~ 
concentration  of  the  bath  it  may  be  observed  that : 

1.  The  absolute  strength  is  almost  independent  of  the  composi- 
tion of  the  bath.     The  results  of  the  series  of  experiments  with 
freshly  made  up  baths  are  very  plainly  different  from  those  with 
old  baths ;  but  in  each  group  similar  current  densities  correspond 
to  nearly  equal  tensile  strengths,  independently  of  what  concentra- 
tion was  used  in  the  bath.    These  values  are  graphically  set  forth 
in  connection  with  the  table. 

2.  The  elastic  limits  and  the  elongations  show  undoubtedly  the 
influence  of  the  concentration  of  the  bath ;  since  as  the  latter  de- 
creases these  physical  values  decrease  also. 

3.  The  values  for  the  toughness  show  such  irregularities  that 
the  correspondence  between  it  and  the  concentration  of  the  bath- 
is  scarcely  to  be  recognized.     Tests  10  and  11  in  particular  are 
quite  isolated  from  the  others.    The  other  values  allow  of  conclu- 
sions respecting  the  variation  of  toughness  with  current  density 
alone,  but  there  are  some  striking  relations  between  the  properties 
of  the  precipitate  and  the  ratio  of  the  concentration  of  the.  bath  to 
the  current-  density. 

The  results  are  given  further  on.  The  following  additional  ex- 
planations may  be  added : 

The  elastic  limit  given  under  i  and  2  is  expressed  by  the  num- 
ber of  kilograms  which  a  bar  of  one  square  centimeter  cross- 
section  can  support  without  producing  a  permanent  elongation  of 
o.ooooi  or  o.oooi  respectively  of  its  length. 

The  hardness  is  expressed  by  the  length  of  a  nick  which  is  pro- 
duced by  a  chisel  upon  which  a  certain  weight  is  allowed  to  fall. 
The  longer  nick  corresponds  therefore  to  a  relatively  softer  cop^-- 
per,  and  conversely. 

The  sheets  distinguished  by  J  are  taken  from  vertical  hang- 
ing plates  in  a  vertical  direction.  Those  distinguished  by  •*»-*• 
are  cut  in  a  horizontal  direction.  There  was  thus  obtained  as 
relative  hardness : 


PHYSICAL   PROPERTIES   OF   COPPER   DEPOSITS  21 

No.  15  =  19.4  from  a  20%   bath  and  4.00  amp/sq.  dm. 

No.  18^19.4      "  "  15$.      "         "     3.23 

No.  20=17.2      "  "  10%     "         "     1.50  " 

No.  21  =  19.7      "  "     5%      "        "     1.30 

It  is  to  be  remarked  that  defects  in  the  -material  would  be  of 
great  influence  upon  the  length  of  the  sheets  after  rupture,  which 
circumstance  may  be  the  cause  of  some  of  the  irregularities  which 
the  values  of  the  toughness  show. 

From  these  investigations  it  must  be  concluded  that  practically 
the  current  density,  partly  also  its  relation  to  the  concentration  of 
the  bath,  determine  the  strength  and  elasticity  of  the  galvanic  de- 
posit. If  the  entire  electrolytic  process  proceeded  perfectly  it  is 
highly  probable  that  the  qualities  of  the  deposit  would  depend 
upon  the  current  density  only ;  this  would  determine  the  crystal- 
line texture  of  the  product  and  the  mechanical  properties  would 
be  in  correspondence  with  it.  But  since  without  doubt  second- 
ary processes  occur  during  the  electrolysis,  the  intensity  of  which 
depend  upon  the  relation  of  the  current  density  to  the  concentra- 
tion of  the  bath,  the  latter  factor  must  also  influence  the  qualities 
of  the  precipitated  metal. 

For  practical  purposes  the  following  rules  may  be  developed 
from  the  above  facts : 

1.  If  copper  of  the  greatest  tensile  strength  and  hardness  is  to 
be  deposited  and  less  weight  is  laid  upon  great  toughness,  high 
current  densities  of  2  to  3  amperes  per  square  decimeter  should 
be  used.     The  electrolyte  must  in  this  case  evidently  be  as  con- 
centrated as  possible  (20  per  cent.). 

2.  If  copper  of  the  greatest  possible  toughness  is  desired,  and 
hardness  and  strength  are  of  less  importance,  current  densities  of 
0.6  to  i  ampere  are  suitable.    The  electrolyte  would  be  a  16  to  18 
per  cent,  solution. 

The  absolute  tensile  strength  of  a  good  galvanic  deposit  approxi- 
mates that  of  cold-hammered  plate  and  its  elastic  limit  in  some 
tests  has  gone  considerably  higher. 

As  far  as  toughness  is  concerned  the  galvanic  deposits  are  con- 
siderably superior  to  the  rolled  metal.  This  is  very  well  deserv- 
ing of  notice. 

As  is  shown  in  experiment  No.  12,  the  cohesion  of  the  precipi- 


22  MANUFACTURE  OF  METALLIC  OBJECTS 

tate  upon  a  vertical  hanging  plate  is  not  the  same  in  all  directions. 
Tensile  strength,  elastic  limit  and  especially  the  toughness  are 
greatest  in  a  vertical  direction.  This  circumstance  is  only  to  be 
explained  by  the  orientation  of  the  crystals,  which  is  influenced 
by  the  upward  flowing  current  of  electrolyte.  This  fact  is  also  of 
practical  value  in  that  it  is  sometimes  desirable  to  put  the  articles 
being  produced  in  such  position  in  the  bath  so  as  to  produce  the 
above  effects  in  certain  desired  directions.  Copper  •  plates  for  en- 
graving are  therefore  always  to  be  produced  in  such  manner  that 
the  strongest  cohesion  of  the  metal  lies  in  the  direction  along 
which  the  plate  passes  in  the  printing  press. 

Experiment  No.  23  is  made  with  a  plate  produced  with  the 
greatest  care  in  a  Daniell  trough  apparatus.  The  apparatus  was 
charged  with  the  so-called  English  vitriol ;  the  measured  current 
strength  was  0.25  ampere.  The  absolute  tensile  strength  and 
toughness  are  in  fact  lower  than  those  made  with  dynamo-electric 
machines,  yet  this  precipitate  is  to  be  regarded  as  a  particularly 
fine  one  in  view  of  the  manner  in  which  it  is  made. 

Appendix  V  of  Hiibl's  "Original-Abhandlung"  shows  the  de- 
formation which  different  precipitates  suffer  under  the  tensile 
tests.  Tests  2  and  3  are  well  worthy  of  notice ;  for  they  have  a 
higher  elastic  limit  than  refined  copper,  and  yet  show  a  surpris- 
ingly good  behavior  on  rupture. 

Foerster  and  Seidel1  took  these  questions  up  later  and  obtained 
results  in  complete  accord  with  those  of  Hiibl.  They  discovered, 
however,  an  important  new  factor;  r/.c:.,  the  influence  of  the  tem- 
perature of  the  electrolyte  upon  the  physical  properties  of  the  cop- 
per. The  following  values  were  found  :2 

Toughness      Per  cent 

Temperature  of  the    Average  bath-tension.         Ri-lative  tensile  elongation  at 

Electrolyte  in  °C.  Volts.  strength-.  rupture. 

20  0.;,2  2.15  9-12 

40  0.25  2.67  26.00 

60  0.20  2.69  13-50 

Drawn  wire  from  Mansfield  „  Q, 

electrolytic  copper. 

It  appears  therefore  that  the  temperature  of  35  to  40°  C.  is  the 

1  Zeitschr.  f.  Elektrochemie  5,  508  et  seq. 

2  These  numbers  represent  the  length  of  a  wire  of  the   metal   in    Kilometers  which 
will  support  its  own  weight.    These  tests  were  made  at  the  Mechanical  Institute  at 
Dresden  by  Dr.  Hartig. 


PHYSICAL   PROPERTIES    OF   COPPER   DEPOSITS  23 

most  suitable,  while  an  elevation  above  this  causes  a  decrease  in 
tensile  strength  of  the  copper.  The  reason  of  the  favorable  action 
of  the  higher  temperature  upon  the  structure  of  electrolytic  cop- 
per was  not  definitely  known.  Foerster1  is  of  the  opinion  that 
the  temperature  of  the  solution  determines  the  size  and  regularity 
of  the  small  crystals  of  the  deposit  and  thus  determines  its  struc- 
ture ;  he  conducted  two  experiments  in  a  bath  which  contained  an 
amount  of  Glauber  salt  equivalent  in  amount  to  the  copper  sul- 
phate present,  along  with  the  usual  amount  of  sulphuric  acid. 

Toughness.    Per  cent 

Temperature  of  the  Tensile  strength  elongation  at 

electrolyte  in  °C.  (relative).  rupture. 

20  2.46  I5-2O 

40  1.96  10.82 

From  this  it  is  to  be  concluded  that  when  alkaline  sulphate  is 
added,  the  increased  temperature  influences  unfavorably  the  phy- 
sical properties  of  the  copper,  while  on  the  other  hand,  the  re- 
sults at  20°  C.  were  better  with  the  addition  of  alkaline  sulphate 
than  without  it. 

The  galvanoplastic  baths  in  ordinary  use  at  present  are  made 
up  according  to  the  principles  above  explained,  and  Hiibl's  and 
Foersters  investigations,  which  furnished  the  foundation  for  the 
present  stage  of  development.  Later  investigations  have  been 
concerned  mostly  with  increasing  the  speed  of  deposition  of  the 
copper  precipitate  and  the  copper  baths  in  practical  use  at  present 
have  been  modified  according  to  the  principles  discovered  by  Carl 
Polenz  and  the  author,2  and  give  precipitates  much  more  quickly 
and  yet  without  a  deterioration  of  the  quality  of  the  cathode  cop- 
per. 

RAPID   DEPOSITION. 

While  Carl  Polenz  used  a  solution  containing  350  grams  of 
copper  sulphate  in  a  liter  of  water  and  warmed  to  30°  C.3  the 
author  used  a  bath  of  the  following  composition : 

Water I  liter 

Copper  Sulphate 250  grams 

Sulphuric  acid 7.5  grams 

Alcohol 5  grams 

1  Zeitschr.  f.  Elektrochemie  5,  511. 

2  Wilh.    Pfanhauser:    "  Elektroplattierung,  Galvanoplastik  und  Metallpolierung," 
4th  Ed.,  1900. 


24  MANUFACTURE  OF  METALLIC  OBJECTS 

This  bath  possesses  a  specific  resistance  of  1.6  ohms  and  a  tem- 
perature coefficient  of  0.0096.  The  temperature  was  about  20° 
C. ;  yet  higher  temperatures,  such  as  are  produced  by  high  current 
densities,  up  to  10  amperes  per  square  decimeter,  are  quite  harm- 
less if  they  do  not  exceed  30°  C. ;  in  fact,  they  exert  a  favorable 
influence  on  the  precipitate.  The  electrolyte  was  kept  in  motion 
by  an  air  blast,  thus  furnishing  concentrated  copper  solution  con- 
stantly to  the  cathode  and  at  the  same  time  cooling  the  solution 
so  as  to  dispense  with  the  use  of  cooling  water. 

OLD  BATHS. 

The  bath  formerly  used  for  galvanoplastics  was  composed  of 

Water i  liter 

Copper  sulphate 200  grains 

Sulphuric  acM 30  grams 

Specific  resistance  0.93  ohm,  temperature  coefficient  O.OH2.1 

POWER  REQUIRED  FOR   COPPER   PRECIPITATION. 

If  the  relative  currents  are  compared,  as  required  for  the  usual 
bath  and  for  the  rapid  deposition  bath  of  Pfanhauser,  the  power 
required  to  deposit  one  kilogram  of  copptT,  the  distance  between 
the  electrodes  being  10  centimeters,  is  as  follows : 

In  Pfanhauser's  rapid 
galvanoplastic  bath. 
Horsepower — Hours. 


4.60 
6.90 
9.20 
If. 50 
13.80 
16.10 
18.40 
20.70 
23.00 

The  power  requirement  is  proportional  to  the  specific  resist- 
ance of  the  electrolyte  as  long  as  no  polarization  phenomena  ap- 
pear, that  is  as  long  as  no  counter  electromotive  force  complicates 
the  calculation.  If  the  Pfanhauser  rapid  deposition  bath  is  kept 
in  use  for  a  long  time  the  electrolyte  becomes  impoverished  in 
free  sulphuric  acid  and  therefore  acid  must  be  added  from  time 
to  time. 

1  As  measured  by  the  author. 


Current  density  in 
amperes  per 
square  decimeter. 

In  ordinary  galvano- 
plastic bath. 
Horsepower  —  Hours. 

0-5 

0.67 

1.0 

J-34 

i-5 

2.01 

2.0 

2.68 

3-0 



4.0 

.... 

5-0 

.... 

6.0 



7.0 

.... 

8.0 



9.0 



IO.O 

.... 

IV.    BEHAVIOR  OF  COPPER  ANODES. 


ANODE:  SLIME. 

In  this  field  Hiibl  has  also  made  some  skillful  observations,  and 
Foerster  also  has  given  extensive  communications  on  anode  slimes 
in  the  baths.  Max  Herzog  von  Leuchtenberg  has  also  written 
concerning  the  slime  residue.  Commercial  copper,  not  electroly- 
tic, may  contain  impurities  of  the  most  different  elements,  of 
which  I  may  mention,  Au,  Ag,  As,  Sn,  Pb,  Fe,  Ni,  S,  etc.,  which 
are  usually  known  outside  of  the  copper  refinery. 

But  the  electrolytically  produced  copper,  if  it  has  not  been  roll- 
ed before  being  used  as  an  anode,  also  furnishes  a  reddish  slime 
which  was  investigated  as  early  as  1875  ^Y  Kick.1  He  deter- 
mined that  it  contained  about  60  per  cent,  of  metallic  copper  and 
40  per  cent,  of  cuprous  oxide,  Cu2O. 

Hiibl  does  not  agree  with  Kick  for  he  writes:  "If  what  F. 
Kick  observed  is  correct,  a  part  of  the  SO4  radicle  liberated  at 
the  anode  would  have  to  form  free  sulphuric  acid  and  oxygen. 
In  that  case  the  content  of  the  bath  in  free  sulphuric  acid  would 
increase  after  long  use."  Since  the  quantity  of  the  slime  formed 
when  using  electrolytic  copper  as  anodes  is  in  considerable 
amount,  it  was  interesting  to  further  investigate  this  phenomenon. 

As  far  as  commercial  copper  plates  were  concerned  the  results 
obtained  substantiate  completely  those  of  Leuchtenberg.  The 
quantity  of  black  slime  produced  depends  almost  solely  upon  the 
purity  of  the  metal  and  is  quite  small  when  using  the  better  grade 
of  copper  at  present  found  in  commerce.  Using  electrolytically 
produced  anodes,  however,  there  appears  to  be  produced  a  much 
larger  quantity  of  a  light  brown  slime  which  was  found  to  be 
completely  free  from  foreign  metals.  After  washing  and  drying 
there  remains  a  heavy,  dense,  brittle  mass,  readily  taking  a  cop- 
pery lustre  when  polished.  Under  the  microscope  it  was  seen  to 
be  almost  entirely  composed  of  more  or  less  well  preserved  cop- 
per crystals. 

1  Dingier  Pol.  J.  218,  219. 


26  MANUFACTURE;  OF  METALLIC  OBJECTS 

COMPOSITION  OF  THE  ANODE  SUMS. 

Using  pure  anodes  deposited  electrolytically,  repeated  chemical 
analyses  of  the  residues  showed  them  to  consist  only  of  pure  cop- 
per. The  method  of  Hampe,1  the  determination  of  the  loss  of 
weight  by  ignition  in  a  current  of  hydrogen,  was  used  for  the  de- 
termination of  the  oxygen  present  in  the  residue.  In  two  tests  no 
oxygen  at  all  could  be  found,  and  therefore  Cu2O  could  at  most 
only  have  been  present  in  traces.  If  the  washing  and  drying  of 
the  copper  slimes  has  not  been  done  with  the  proper  care  it  be- 
gins to  take  a  yellow  color  and  in  that  case  considerable  quanti- 
ties of  Cu2O  can  be  found.  A  test  of  a  partly  oxidized  slime  of 
this  nature  showed  a  content  of  4.7  per  cent,  of  Cu2O. 

The  residue  from  galvanic  deposited  anodes  consists  therefore 
of  microscopically  small  copper  crystals  which  have  the  property 
when  used  as  an  anode  of  remaining  unaltered.  It  is  highly 
probable  that  they  really  exist  in  a  passive  state  which  may  be 
due  to  an  extremely  thin  coating  of  cuprous  oxide,  Cu2O,  not  de- 
tectable analytically.  Only  galvanic  deposited  copper  shows  this 
phenomenon,  which  may  be  explained  by  its  quite  characteristic 
crystalline  structure. 

INFLUENCE  OF  THE  ANODE  SLIME  ON  THE  PRECIPITATE. 

This  copper  slime  thus  formed  is  a  highly  undesirable  material 
for  the  galvano-plater,  since  it  causes  a  turbidity  in  baths  which 
are  agitated,  becomes  entangled  in  the  precipitated  copper,  causes 
rough  surfaces  and  lowers  the  cohesive  strength  of  the  metal. 

On  these  grounds  it  is  desirable  to  use  commercial  rolled  cop- 
per plates  in  preference  to  the  electrolytically  deposited. 

All  the  observations  so  far  made  concerning  anode  slime  relate 
to  acid  baths.  When  using  the  so-called  neutral  baths  the  forma- 
tion of  cuprous  oxide,  Cu2O,  can  be  actually  observed,  particu- 
larly when  high  current  densities  are  used.  The  anode  in  this 
case  becomes  at  places  plainly  reddish  yellow  and  under  this  con- 
dition the  bath  shows  a  change  in  its  acidity  after  the  electrolysis. 

Foerster  also  finds  only  a  small  amount  of  cuprous  oxide,  Cu2O, 
and  determined  that  it  consisted  likewise  of  small  crystals  of  pure 
copper.  He  explained  the  formation  of  these  small  crystals  by 

1  Zeitschr.  f.  anorgan.  Chemie  13,  202. 


BEHAVIOR  OF  COPPER  ANODES  27 

the  increase  in  the  concentration  of  the  solution  in  the  neighbor- 
hood of  the  cathodes  which  were  surrounded  loosely  with  parch- 
ment paper ;  and  by  the  tendency  of  the  anode  copper  to  furnish 
copper  ions  to  the  solution,  producing  in  the  immediate  vicinity  of 
the  anode  cuprous  sulphate,  Cu2SO4,  which  decomposed  sponta- 
neously into  cupric  sulphate,  CuSO4,  and  the  crystalline  precipi- 
tate of  copper. 

+       +  + 
2  Cu  =  Cu 

Cu-f  Cu  =  Cu2SO4, 

+  + 

Cn2SO4  =  CnSO4  -f  Cu. 

POLARIZATION  PHENOMENON. 

The  author  has  observed  that  when  using  envelopes  of  parch- 
ment paper,  silk,  etc.,  around  the  anode  the  current  strength  falls 
soon  after  closing  the  circuit,  instead  of  remaining  constant,  and 
in  this  case  reaches  constancy  only  at  a  small  fraction  of  an  am- 
pere. But  since  it  is  desirable  at  times  to  keep  the  anode  slime 
out  of  the  body  of  the  electrolyte,  particularly  when  the  baths  are 
agitated,  in  order  not  to  interfere  with  the  physical  properties  of 
the  precipitated  copper,  I  began  investigations  to  find  a  suitable 
envelope  which  would  be  close  enough  to  retain  fine  slime  and  on 
the  other  hand  sufficiently  porous  to  keep  down  the  tendency  to 
increased  concentration  inside  the  envelope,  which  occurs  par- 
ticularly with  high  current  densities.  Flannel  not  too  tightly 
woven  was  found  to  be  the  only  suitable  material.  Using  current 
densities  of  even  8  amperes  per  square  decimeter  and  envelopes 
of  this  material,  there  was  no  sign  of  the  falling  off  of  the  cur- 
rent after  closing  of  the  circuit  and  the  solution  remained  clear 
of  slime  even  when  the  so  much  feared  electrolytic  anodes  were 
used.  In  this  manner,  plates  4  to  5  millimeters  in  thickness  were 
produced,  using  current  densities  of  8  amperes  per  square  deci- 
meter and  having  only  very  small  unevenness  on  the  depositing 
surfaces. 


V.    CONSTANTS  OF  THE  BATH  AND  CALCU- 
LATION OF  THE  AMOUNT  OF  DEPOSIT. 


The  operation  of  plants  for  the  electrolytic  manufacture  of  me- 
tallic objects  must  be  so  arranged,  it  will  be  admitted,  that  even 
the  workmen  may  be  able  to  determine  at  once  whether  their 
baths  are  working  or  not.  For  this  reason,  each  bath  must  be 
supplied  with  an  ammeter  and  a  voltmeter,  as  well  as,  when  neces- 
sary, a  regulating  resistance  either  in  series  or  in  parallel  with 
the  bath ;  we  will  speak  later  of  this.  Since  the  ordinary  work- 
man having  charge  of  the  bath  cannot  be  expected  to  be  able  to 
calculate  specific  bath  resistances,  current  density,  etc.,  it  is  neces- 
sary to  give  him  precise  data  concerning  the  proper  indication  of 
his  instruments,  from  which  he  can  draw  conclusions  concerning 
the  correct  working  of  his  bath.  On  the  contrary,  the  constants 
of  the  bath  should  be  known  to  the  person  in  charge,  and  I  will 
therefore  at  this  place  recapitulate  briefly  the  methods  of  deter- 
mining them. 

DETERMINATION    OF   THE    SPECIFIC    RESISTANCE. 

In  Fig.  I,  A  A,  indicates  a  stretched  wire  of  "constantin"  serv- 
ing as  a  measuring  wire  and  provided  with  a  millimeter  scale. 


"WWvVvVWW 

A/WW\ 


Fig.  i. 


From  the  point  A  a  conductor  leads  to  the  Arrhenius  cell  W, 
which  contains  the  electrolyte  to  be  investigated  and  whose  other 
pole  is  in  connection  through  B  with  the  plug  rheostat  R,  and 


CALCULATION  OF  THE)  AMOUNT  OF  DEPOSIT  29 

through  it  to  the  other  end  A,  of  the  measuring  wire.  Between 
the  point  and  the  movable  wire  contact  K  there  is  inserted  a  Bell 
telephone  T,  which  gives  a  sound  by  means  of  the  alternating  cur- 
rent generated  in  the  induction  coil,  so  long  as  a  current  flows 
through  the  telepone.  By  suitably  changing  the  resistance  in  R 
and  sliding  of  the  contact  K,  the  current  through  the  telephone 
can  be  brought  to  zero  when  the  potential  fall  through  BR  is 
equal  to  the  potential  fall  through  the  other  side  of  the  circuit. 
The  relation  of  resistance  at  this  point  is  therefore 

a__  W 

~J~  :R 

the  latter  reading  being  the  relation  of  the  distances  AK  and  Alf 
K,  respectively,  as  measured  in  millimeters,  and  on  the  further 
assumption  that  the  measuring  wire  has  a  constant  resistance  for 
uniform  distances  on  the  scale.1  (For  the  most  accurate  work  the 
measuring  wire  should  be  calibrated).  From  the  above  propor- 
tion the  resistance  of  the  cell  W  between  the  two  platinized  elec- 
trodes of  the  Arrhenius  vessel  is  calculated,  that  is 

Resistance  of  cell  =-  —  X  Resistance  of  plug  rheostat. 

W  being  known,  the  determination  of  the  specific  resistance  of 
the  electrolyte,  Rr)  taking  as  a  practical  unit1  a  cube  of  the 
fluid  one  decimeter  on  a  side,  may  be  found  by  dividing  R  by  the 
resistance  capacity  K  of  the  measuring  vessel,  in  which  K  is  the 
ratio  of  the  length  to  the  cross-section  of  the  electrolytic  resist- 
ance measured,  this  proportion  being  called  the  resistance  capacity 
of  the  measuring  vessel.  This  proportion  can  be  gotten  by  meas- 
usement,  or  by  an  experimental  determination  by  placing  in  the 
vessel  a  fluid  of  known  specific  resistance,  and  measuring  the  re- 
sistance of  the  vessel,  so  that  the  actual  resistance  divided  by  the 
specific  resistance  of  the  fluid  gives  the  ratio  K  for  the  vessel 
-.used.2 

1  See  Kohlrausch  and  Holborn. 

2  The  specific  resistance  of  fluids  is  usually  expressed  in  the  tables  as  that  of  a  centi- 

meter* of  the  liquid,  which  value  is  ten  times  the  value  Rs  chosen  as  the  unit  by 
Mr.  Pfanhauser  and  attention  should  be  paid  to  this  difference  when  using 
Pfauhauser's  formula  and  taking  the  specific  resistance  from  the  ordinary 
tables. — TRANSLATOR. 


3O  MANUFACTURE  OF  METALLIC  OBJECTS 

As  an  example,  the  resistance  K  of  an  Arrhenius  cell  was  found 
to  be  0.2,  and  the  actual  resistance  of  the  unknown  fluid  was  0.3 
ohm,  from  which  the  specific  resistance  of  the  unknown  fluid  was 

calculated  to  be  —  =  1.5  ohms. 

For  further  details  to  be  observed  in  this  measurement,  such  as 
the  choice  of  the  calibration  fluid,  choice  of  the  form  of  the  meas- 
uring vessel,  etc.,  reference  is  made  to  the  work  of  Kohlrausch 
and  Holborn,  "Das  Leitvermogen  der  Elektrolyte." 

CALCULATION  OF  THE  BATH  TENSION. 

When  one  knows  the  specific  resistance  of  the  electrolyte,  then,, 
if  the  distance  of  the  electrodes  apart  and  their  sizes  are  carefully 
measured,  the  total  resistance  of  the  bath  R^  is  equal  to  the 
specific  resistance  multiplied  by  the  length  of  the  bath  betweeri 
the  electrodes  and  divided  by  its  cross-section. 

_R,X/ 
R'~   ~7~ 

In  this  formula  s  is  the  active  cross-sectional  area  of  the  elec- 
trolyte and  /  the  mean  distance  apart  of  the  electrode  surfaces 
from  each  other  expressed  in  square  decimeters  and  decimeters 
respectively.  In  order  to  send  through  the  bath  with  a  resistance 
R£,  a  current  of  A  amperes,  a  potential  difference  V  volts  is  nec- 

V  =  AR  =  A.R,  — 

s 

4^ 

essary.     If  — is  assumed  to  be  the  current  density  per  square 

decimeter  (ND/ioo)  and  if  the  alteration  of  the  resistance  with 
the  temperature  is  taken  into  account,  we  have  the  relation 

V  =  ND1M./.R,  (i±«0 

If  the  counter  electromotive  force  Vrf  enters  into  the  galvanic 
process,  its  amount  (expressed  in  volts)  appears  on  the  right  side 
of  the  above  equation;  so  that  the  expression  for  the  total  bath 
tension  will  be 

V  =  ND100./- W,  (i  ±  a  t)  +  Vrf. 

GROWTH  IN  THICKNESS  OF  GALVANIC  DEPOSITS. 

To  calculate  the  growth  in  thickness  of  galvanic  deposits  the 


CALCULATION  OF  THE  AMOUNT  OF  DEPOSIT  3! 

•current  density  used  and  the  duration  of  the  electrolysis  are  the 
-determining  factors.  A  third  factor  is  the  electrochemical  equiv- 
alent of  the  metal  being  precipitated  from  the  solution  used. 
There  are,  for  instance,  two  different  rates  of  precipitation  of 
copper  according  to  whether  it  is  precipitated  from  cuprous  or 
cupric  salt  solutions.  According  to  Faraday's  Law,  96,540  cou- 
lombs separate  a  gram-equivalent  of  metal,  or  in  round  numbers, 
26.8  ampere-hours  are  necessary,  as  a  practical  unit. 

So  the  amount  of  copper  precipitated  by  an  ampere-hour  is 
3.272  grams  from  a  cuprous  solution  and  1.186  grams  from  a  cup- 
Tic  solution. 

The  amount  of  metal  precipitated  in  a  given  time  t  in  hours  by 
a  given  current  A  in  amperes  and  with  an  efficiency  in  precipita- 
tion e  expressed  in  percentage,  would  be,  calling  the  amount  of 
metal  precipitated  by  one  ampere-hour  W. 

W=  W.-A./.    — 

100 

[This  value  of  W,  would  be  3,600  times  the  usual  electrochem- 
ical equivalent  of  the  metal ;  that  is,  the  amount  precipitated  by 
one  ampere-second  or  one  coulomb. — Translator.] 

Calling  D  the  specific  gravity  of  the  precipitated  metal,  the 
thickness  T  in  millimeters  of  the  metal  deposited  on  the  cathode 
of  surface  S 

Wr       W.  (ND.J  X, 


D.  1000 

From  this  equation  any  single  value  can  be  easily  obtained ;  thus 
for  instance  the  time  in  which  a  given  current  density  must  act  in 
order  to  obtain  a  deposit  of  a  given  thickness 

_     T.  D.IOOO 

The  current  density  to  be  used  (ND/ioo)  will  be  expressed  by 
the  formula 

T. D.IOOO 
N  D100  = amperes. 

1 

The  subsequent  tables  contain  numerous  examples  and  refer- 
ences may  be  made  to  them. 


/ 


O     THE 


VL     INDUSTRIAL  PLANTS. 


Before  passing  to  the  practical  operation  of  the  different,  pro- 
cesses, I  will  give  a  few  further  fundamental  points  concerning 
the  equipment  of  the  plants,  such  as  may  not  he  unwelcome  to  the 
manufacturer. 

SOURCE  OF  CURRENT. 

First  of  all  concerning  the  source  of  current,  there  is  seldom 
above  15  volts  tension  needed  at  the  dynamo-machine  because 
greater  tensions  are  unsuitable  from  the  danger  of  the  ground, 
connection  which  may  be  made  through  the  tanks.  We  are  deal- 
ing also  with  well  conducting  solutions  and  during  the  manipula- 
tion of  the  cathodes,  their  taking  out  and  putting  in,  naturally 
some  of  the  fluid  is  spilled  and  may  cause  ground  connections. 


Fig.  2. 
TANKS. 

The  tanks  for  electrolytic  use  are  almost  universally  made  of 
larch  or  pitch  pine  wood,  vessels  of  earthenware  or  cement  being 
seldom  used.  The  wooden  vessels  have  as  their  greatest  advant- 
age the  slight  danger  of  being  broken,  and  besides  auxiliary  ap- 
paratus can  easily  be  fastened  to  wooden  tanks ;  for  instance,  stir- 
ring apparatus  and  the  like. 

Fig.  2  shows  a  wooden  tank  such  as  is  used  in  the  manufacture 


INDUSTRIAL,  PLANTS  33 

of  metallic  papers.  Such  vessels  are  usually  rated  according  to 
contents  and  the  following  table  gives  the  approximate  prices 
which  the  various  sizes  cost,  on  the  average,  per  unit  of  contents. 

Cost  per  liter  of 
Capacity.  capacity. 

100  liter  7.5  cents 

100 — 150  5.0      " 

150—200  4.5  " 

200 — 250  4.0  " 

250—300  3.5  " 

300—400  3.0  " 

400—500  2.7  " 

500—600  2.5  " 

6OO — 8OO  2.2    " 

SOO  —  TOOO  2.1    " 

Over  1000  1.7 — 2.0      " 

It  is  recommended  to  set  all  tanks  on  a  cement  floor  so  that 
they  do  not  warp  and  leak  as  they  would  do  on  a  wooden  floor. 

CONNECTING  UP  OF  THE  BATHS. 

On  a  large  scale  when  certain  duplicate  objects  are  being  pro- 
duced, a  series  connection  of  the  bath  is  to  be  recommended  for 
many  reasons,  because  in  that  manner  the  production  becomes 
more  uniform.  When  connecting  in  series,  there  is  an  assurance 
that  the  cathodes  all  receive  the  same  amount  of  metal,  will  all  be 
ready  at  the  same  time,  and  must  be  of  similar  quality.  It  is  self- 
evident  that  the  electrode  surfaces  in  the  several  baths  must  be 
alike. 

If  there  are  considerable  differences,  however,  in  the  sizes  of 
the  objects  when  many  small  pieces  are  to  go  into  one  bath,  it  is 
necessary  to  use  parallel  connection  of  the  baths,  or  regulating 
resistances  connected  up  in  parallel  to  each  one  of  the  baths  which 
are  in  series.  These  rheostats,  in  combination  with  the  resistance 
of  the  bath  thus  provide  a  normal  resistance  of  the  cell  unit. 

A  schematic  diagram  of  such  plants  is  shown  in  Fig.  3.  DM  is 
the  dynamo-machine  furnishing  current,  AM  is  the  principal  am- 
meter. The  nine  baths  are  divided  into  three  groups  connected 
in  series,  each  group  consisting  of  three  baths  in  parallel.  Each 
series  has  a  regulating  resistance  RWI,  RWII,  and  RWIII,  re- 
spectively, connected  in  parallel. 


34 


MANUFACTURE;  OF  METALLIC  OBJECTS 


If,  for  instance,  R  is  the  total  resistance  of  a  single  bath,  R± 
that  resistance  which  exists  in  a  similar  bath  with  a  smaller 
cathode  surface,  then  it  is  necessary  to  put  in  parallel  with  this 
series  a  resistance  R2,  which  in  connection  with  the  resistance  Rx 
will  give  a  normal  resistance  R. 


Fig-  3- 

The  method  of  connection  must  therefore  fulfill  the  condition 
expressed  by  the  formula 

-- 


X  R2 

A  voltmeter  attached  to  the  ends  of  the  rheostat  shows  to  the 
workman  whether  the  adjustment  has  been  properly  made,  since 
the  normal  current  density  will  be  present  in  the  bath  when  the 
voltmeters  of  the  separate  baths  are  alike.  If  the  voltmeter  reads 
below  the  normal  bath  tension,  then  too  great  a  current  is  passing 


INDUSTRIAL  PLANTS 


35 


through  the  rheostat  and  too  small  a  current  through  the  bath 
and  the  latter  is  working  with  too  small  a  current  density ;  in  this 
case  the  resistance  of  the  rheostat  should  be  increased  until  the 
voltmeter  indicates  the  normal  bath  tension. 

PARALLEL  CONNECTING  OF  THE  BATHS. 

When  the  baths  are  connected  in  parallel,  the  rheostats  are  con- 
nected in  series  with  the  baths  so  that  the  bath-current  goes 
through  the  rheostat.  This  provides  a  means  of  reducing  the 
voltage  of  the  system  down  to  a  normal  bath  tension  or  of  mak- 
ing the  bath  tension  smaller  in  order  to  produce  a  normal  current 
density  when  there  are  smaller  cathode  surfaces  in  the  bath,  which 
disturb  the  relation  between  the  anode  and  cathode  surfaces. 

The  regulating  resistance  then  absorbs  the  voltage  V.f-v  ;  that 
is,  it  causes  this  drop  of  potential  when  the  bath  current  passes 
through  it.  Its  maximum  resistance  is  therefore: 

V — v 

R  (max)  =  -:— — r-r 
A  (mm) 


Fig.  4  shows  this  method  of  connecting  used  for  two  baths. 
BRj  and  BR2  are  the  bath-current  regulators  for  the  baths  Bt  and 
B2.  The  voltmeters  VMX  and  VM2  are  in  parallel  with  the  elec- 
trodes, a  and  b  are  the  main  conductors,  DM  the  central  dynamo, 
MW  the  shunt  winding,  NR  the  field  regulator,  BS  the  lead  fuse, 


36  MANUFACTURE  OF  METALLIC  OBJECTS 

AM  the  main  ammeter,  HA  a  single  pole  hand  switch,  and  VU 
a  voltmeter  switch  for  the  voltmeter  VM.  The  voltage  of  the 
system,  V,  measured  by  placing  the  voltmeter  switch  on  the  ar- 
restment  2,  is  held  constant  by  the  shunt  regulator,  and  the  bath 
tension  is  adjusted  by  the  regulator  BR^  and  BR2. 

THE  CONDUCTORS. 

It  naturally  can  not  be  within  the  scope  of  this  work  to  treat  of 
the  calculation  of  the  conductors.  I  will  limit  my  observations  to 
what  I  regard  as  normal :  the  drop  of  potential  in  the  conductors 
should  not  be  greater  than  7.5  per  cent,  of  the  voltage  at  the 
dynamo  terminals,  whether  either  parallel  or  series  connection  is 
used.  The  plant  with  series  connections  necessarily  works  better 
from  a  financial  standpoint  because  the  cross-section  of  the  con- 
ductors is  much  smaller,  also  the  contact  surfaces  at  the  joints  of 
the  conductors  may  be  lighter. 

On  the  other  hand,  the  insulation  is  simpler  with  parallel  con- 
necting and  therefore  in  many  plants  a  mixed  connection  such  as 
is  shown  in  Fig.  3  has  been  found  most  suitable. 


VII.     PARTICULAR    DEVICES    FOR    SPECIAL 

PURPOSES.    PRODUCTION  OF  UNIFORM 

DEPOSITS. 


DISTRIBUTION  OF  CURRENT  LINKS. 

If  the  current  is  allowed  to  pass  from  an  anode  of  any  size  to  a 
smaller  cathode,  without  taking  particular  precautions,  it  is  often 
found  that  the  edges  and  such  parts  of  the  cathode  which  hang 
closer  to  the  anode  are  more  heavily  coated  with  deposit  than  the 
other  parts.  The  explanation  of  this  is  as  follows :  the  separate 
surface  elements  of  the  cathode  and  those  of  the  anode  form  in 
combination  \vith  the  corresponding  cross-section  of  the  electro- 
lyte a  total  resistance  R  which  is  formed  of  the  parallel  single  re- 
sistance elements  r.  According  to  Kirchoff,  however,  the  total 
current  A  must  distribute  itself  in  proportions  corresponding  to 
the  conductivities  of  the  separate  resistance  elements.  With 
equal  distances  between  all  of  the  cathode-surface  elements  and 
the  corresponding  anode-surface  elements  (assume  these  elements 
i  square  centimeter  each),  there  will  result  an  equivalence  of  the 
separate  resistance  elements,  giving  them  the  values ; 

__  /  X  IPO 

:~r^rr 

the  result  being  in  ohms  if  /  is  the  distance  of  the  electrode  sur- 
face elements  from  each  other,  in  decimetres,  k  is  the  conductivity 
of  the  electrolyte  per  decimetre,3  and  j  is  the  cross-section  (say 
one  square  centimeter)  of  the  conducting  fluid. 

In  case  that  the  anode  as  well  as  the  cathode  form  the  end  sur- 
faces of  th$  trough  and  are  parallel  to  each  other  and  reach  to  the 
surface  of  the  fluid,  all  the  resistance  elements  in  the  fluid  are 
equal.  Or  if  it  is  possible  that  there  is  a  certain  cross-section  of 
electrolyte  above  the  edges  of  the  cathode,  then  current  lines  di- 
verge into  this  space  and  concentrate  down  upon  the  edges  of  the 
cathode.  The  consequence  is  that  the  sum  of  these  lines 

v  /  X    IPO 


3§  MANUFACTURE  OF  METALLIC  OBJECTS 

will  increase  the  current  density  upon  the  cathode  edges,  where- 
by an  inequality  of  the  rate  of  growth  takes  place. 

The  case  is  similar  if  projecting  parts  of  the  cathode  or  anode 
reduce  the  length  /  of  the  resistance  elements.  This  results  in  in- 
creasing the  current  density  on  the  electrode  surface  elements 
concerned  and  increases  the  influence  of  electrolysis  upon  cathode 
or  anode. 

UNIFORM   DEPOSITS. 

Fletcher1  obtained  uniform  deposits  by  rotating  the  cathode 
and  arranging  the  anodes  at  a  certain  distance  from  it.  It  may  be 
remarked  that  Fletcher's  method  can  be  improved  if  the  various 
distances  for  the  anodes  are  worked  out  graphically. 


Figs.  5.  6,  7. 

Engelhardt2  made  the  further  improvement  by  eliminating  the 
errors  which  could  not  be  avoided  by  rotating  the  cathode  alone, 
by  rotating  the  anode  as  well  as  cathode.  Thus,  by  varying  at 

i  American  Patent,  485,  343— Lum.  El.  1892,  47,  32. 
American  Patent  544,  668,  Aug.  20,  1895.     See  also  Zeitschr.  f.  Elektrochemie  2,  408. 


PRODUCTION  OF  UNIFORM  DEPOSITS  39 

times  the  initial  velocity  of  rotation,  the  average  current  density 
on  all  parts  of  both  cathode  and  anode  can  be  kept  alike,  whereby 
a  uniform  growth  of  the  deposit  and  a  uniform  solution  of  the 
anode  would  be  obtained. 

The  apparatus  proposed  by  Engelhardt  for  obtaining  these  ends 
is  shown  in  Figs.  5,  6,  and  7. 

The  contact  strips  /  are  placed  upon  the  edge  of  the  decomposi- 
tion cell  a.  Upon  these  rest  the  cathode  carriers  b  of  non-con- 
ducting material  having  metallic  strips  m  underneath.  At  right 
angles  above  them  are  the  anode  carriers  c,  which  are  provided 
with  the  conducting  strips  k  on  their  upper  surface.  The  elec- 
trodes e  and  gf  fastened  to  rods  f  and  j,  are  hung  to  their  supports 
by  the  clamps  d  and  so  connected  with  the  conductors. 

The  collars  v  are  movable  upon  the  rods  e  and  g  and  can  be 
clamped  by  screws  and  so  hold  the  electrodes  in  the  guides  d. 
The  electrodes  can  be  rotated  by  means  of  the  rope  pulleys  i  and  h. 
PROCESS  OF  BAUER. 

J.  G.  Bauer1  patents  the  following  process  for  the  manufacture 
of  curved  bodies  which  must  be  precipitated  upon  moulds  having 
the  corresponding  projections. 

Patent  Claims. 

1.  A  process  for  the  production  of  uniform  galvanic  deposits 
upon   non-conducting   bodies,   characterized   by   having   metallic 
chains  inserted  into  the  cores,  the  links  of  which  appearing  at  the 
surface  of  the  core  form  points  of  attachment  for  the  galvanic 
precipitate. 

2.  The  use  of  the  principles  of  Claim  i  applied  to  cast  articles 
of  wax,  gypsum,  etc.,  consisting  of  inserting  through  these  bodies 
metal  wires  provided  with  heads  or  enlargements,  in  such  man- 
ner that  one  end  of  the  metal  wire  appears  at  the  upper  surface  of 
the  body  while  the  other  end  is  connected  with  the  main  current 
conductor. 

PROCESS  OF  ANDERSON. 

Anderson2  worked  similar  to  Fletcher,  surrounding  a  rotating 
cathode  core  by  anodes  arranged  around  it  concentrically  as 
anode  strips. 

1  German  Patent  65,  819,  Feb.  6,  1892. 

2  American  Patent  534,  942,  Feb.  26,  1895. 


4O  MANUFACTURE  OF  METALLIC  OBJECTS 

WURTTEMBERG  PROCESS. 

The  superintendent  of  the  Wiirttemberg1  Metal  Ware  Works 
made  an  important  advance  in  this  special  line,  useful  in  case  that 
a  non-uniform  division  of  the  precipitate  \vas  desired,  where  for 
instance  certain  projecting  parts  of  the  finished  article  were  de- 
sired to  be  more  thickly  coated.  This  is  obtained  by  placing  in 
the  bath  between  the  article  and  the  anode,  plates  of  insulating- 
material,  such  as  glass,  etc.,  which  are  provided  with  openings 
and  result  in  largely  cutting  off  the  current  from  the  parts  which 
are  covered  and  increasing  the  current  passing  to  the  parts  imme- 
diately behind  the  openings,  so  as  to  produce  at  will  a  non-uniform 
distribution  of  the  current. 

These  plates  may  be  called  screens  or  current-line  deflectors. 
If  the  opening  in  the  distributor  is  for  instance  circular,  then  the 
current  lines  form  approximately  a  paraboloid  of  revolution  and 
the  projection  of  the  latter  upon  an  article  gives  the  desired  dis- 
tribution upon  the  cathode.  Self-evidently,  the  projection  surface 
upon  the  cathode  varies  with  the  distance  of  the  deflector  from  it 
and  if  the  latter  is  at  a  great  distance,  the  projection  becomes 
blurred  and  disappears. 

The  process  is  protected  by  the  following  patent  claim : 

Patent  Claim. 

Process  for  the  simultaneous  obtaining  of  galvanic  metallic  de- 
posits of  varying  thickness  upon  the  same  object,  produced  by 
arranging  between  the  latter  and  the  anode  freely  hanging  plates 
of  insulating  material. 

Extension  of  the  Process. 

These  cleverly  designed  aids  can,  as  has  been  proved  by  the 
inventor,  be  used  in  order  to  produce  heavy  precipitates  upon  the 
deeper  lying  parts  of  the  mould,  in  the  production  of  curved  ob- 
jects :  this  is  done  by  arranging  the  perforated  shields  before  the 
cathode  with  the  opening  so  arranged  that  the  resistance  capacity 
of  the  elements  of  the  cathode  surface  at  the  deeper  lying  parts  is 
made  equal  to  that  of  the  other  parts  of  the  object. 

Figs.  8  and  9  will  illustrate  this. 

l  German  Patent  76,  975,  July  30,  1893. 


PRODUCTION  OF  UNIFORM   DEPOSITS 


If  the  cathode  K  is  hung  opposite  to  the  anode  A  with  no  special 
precautions,  then  with  the  electrodes  at  too  small  a  distance  apart, 
•great  differences  will  occur  in  the  values  of  the  resistance  ele- 
ments, resulting  in  excess  of  current  density  around  the  point  S. 
But  if  it  is  desired  to  coat  over  the  whole  spherical  surface  uni- 
formly, then,  as  is  shown  in  Fig.  9,  a  shield  is  placed  before  the 
object  in  such  a  manner  that  the  apertures  ooz\  are  in  the  position 
shown.  The  course  of  the  current  lines  will  be  thus  deflected, 
until  they  will  distribute  themselves  nearly  uniformly  over  the 
whole  cathode  surface. 

As  long  as  the  condition    -  --    =  const,  is    fulfilled  for  all  the 

elements  of  the  cathode  surface,  the  distribution  of  current-lines 
will  be  equal  upon  all  parts  of  the  cathode,  producing  a  uniform 
deposit. 


Fig.  8.  Fig.  9. 

For  sharp  corners,  the  division  is  rather  more  difficult.  The 
investigations  of  the  author  have  shown  an  analogy  between  the 
path  of  the  current-lines  and  the  distribution  of  the  magnetic 
lines  of  force  and  has  shown  that  with  larger  electrode  surfaces, 
above  I  square  decimeter,  and  with  electrode  distances  of  more 
than  5  decimeters,  the  scattered  current-lines  will  be  more  than 
25  to  30  per  cent,  of  the  number  of  current-lines  which  would 
exist  in  a  homogeneous  field  between  two  plane  parallel  electrodes. 
The  amount  of  the  scattering  of  the  current-lines  increases  with 
•the  distance  of  the  electrodes  apart  and  decreases  with  the  size  of 
the  electrode  surfaces.  The  following  expression  will  serve  to 
approximately  indicate  the  value  of  the  coefficient  of  scattering, 

f         1.25  X  /X  a 
coef.  =  - 

s 


42  MANUFACTURE  OF  METALLIC  OBJECTS 

where  a  is  a  factor  depending  on  the  conductivity  and  upon  the 
electrolyte.  Only  a  few  very  approximate  values  have  so  far  been 
obtained1  for  this  factor  and  it  can  only  be  said  that  in  equally 
good  conducting  alkaline  or  cyanide  solutions  the  coefficient  of 
scattering  of  current-lines  is  greater  than  in  acid  solutions. 

DUMOULIN  PROCESS. 

The  process  of  E.  Dumoulin2  is  somewhat  connected  with  a 
screen  process.  Dumoulin  used  his  process  for  the  production  of 
objects  with  surfaces  of  rotation,  basing  it  on  the  principle  that 
inequalities  in  the  surface  of  the  precipitate  are  caused  by  un- 
equal distribution  of  the  molecules  and  especially  by  rough  places 
upon  the  cathode.  If  an  unevenness  exists  upon  the  cathode  either 
before  the  current  is  started  or  afterwards,  or  as  a  result  of  the 
poor  precipitation  of  the  metal  resulting  from  a  bad  preparation 
of  the  form  or  by  a  deposition  of  the  slimy  impurities  from  the 
electrolyte,  Dumoulin  insulates  these  points  of  unequal  deposit 
until  the  surrounding  parts  have  reached  the  same  thickness. 

The  process  is  protected  by  the  following  patent  claim. 

Process  for  the  manufacture  of  uniform  electrolytic  metallic 
deposits  consisting  in  placing  upon  the  cathode  during  the  pre- 
cipitation insulating  material ;  producing  this  effect  in  a  manner 
similar  to  the  inking  of  type ;  reintroducing  the  surface  into  the 
bath  wherein  the  insulating  material  itself  is  slowly  removed,  but 
not  before  the  points  coated  have  disappeared  and  become  uni- 
form with  the  whole  surface  of  the  cathode. 

The  Insulating  Material. 

The  materials  used  for  insulation  are  tar,  fat,  vaseline,  albumen 
and  the  like  and  the  quantity  of  the  insulating  material  used  can 
be  regulated  by  the  workman  in  charge,  and  the  growth  of  the 
surrounding  deposit  is  thus  regulated.  It  is  clear  that  the  cur- 
rent density  will  have  a  certain  influence  on  the  kind  of  insulating 
material  used  as  well  as  the  frequency  with  which  the  application 
is  made. 

The  applications  of  this  process  are  more  extensively  described 
later  (see  page  125). 

1  See  Zeitschr.  f.   Elektrochemie  7,  895.     Dr.  W.   Pfanhauser,  "Ueber  die  Streuung 

der  Stromlinien  in  Elektrolyten." 

2  German  Patent  84,  834,  April  9,  1895;  English  Patent  16,  360,  August  31,  1895. 


PRODUCTION  OF  UNIFORM  DEPOSITS  43 

METHOD  OF  THE  FRENCH  COPPER  COMPANY. 

The  Societe  des  Cuivres  de  France1  in  1894  obtained  a  patent 
based  on  the  following  principles : 

If  these  conditions  which  are  necessary  for  the  obtaining  of  uni- 
form deposits  are  not  fulfilled,  irregularities  will  necessarily  ap- 
pear, so  that  often  with  the  most  varied  shaped  anodes  or  even 
by  arrangement  of  anode  strips  around  the  cathode,  the  irregular- 
ities cannot  be  entirely  overcome. 

The  point  referred  to  consists  in  surrounding  the  rotating 
cathode  with  anodes  which  are  provided  with  projections  or  in 
general  with  equal  "unevennesses."  There  is  thus  produced  upon 
the  rotating  cathode  a  corresponding  unevenness  in  the  precipi- 
tate. The  author  believes  the  process  to  have  a  very  limited  appli- 
cation because  slight  projections  on  the  anodes  will  soon  be  dis- 
solved off  and  then  will  exert  no  further  influence. 

Devices  for  Loosening  of  the  Precipitates. 

The  precipitates  are  made  upon  particular  forms,  which,  if  of 
non-conducting  material  such  as  wax,  gutta-percha,  plaster  of 
Paris,  etc.,  must  be  made  conducting  by  suitable  surfaces  of  con- 
ducting material,  such  as  graphite,  finely  divided  silver,  etc.  Me- 
tallic forms  are  often  used  which  are  given  an  intermediate  con- 
ducting coat  if  it  is  desired  to  remove  the  metallic  precipitates 
upon  them ;  the  coating  must  be  of  such  a  nature  that  it  does  not 
combine  with  the  metal,  and  yet  does  not  hinder  the  conduction 
of  the  current.  For  such  intermediate  coatings  the  sulphides  of 
the  heavy  metals  may  be  used,  or  the  metallic  surfaces  may  be 
iodized  or  greased.  W.  Wood2  proposed  the  graphitizing  of  non- 
conducting forms  by  the  use  of  rubber  dissolved  in  linseed  oil; 
the  further  description  of  this  is  given  in  the  special  applications 
of  galvanoplasty. 

PROCESS  OF  SUTHERLAND. 

W.  S.  Sutherland3  manufactured  surface  condensers  by  the 
precipitation  of  metal  upon  an  easily  fusible  core,  which  was  melt- 
ed out  at  the  completion  of  the  precipitation. 

1  English  Patent  23,  679,  Dec.  5,  1894. 

2  English  Patent  Oct.  30,  1873. 

3  English  Patent  8054,  May  22,  1884. 


44  MANUFACTURE  OF  METALLIC  OBJECTS 

PROCESS  OF  REINFELD. 

A.  K.  Reinfeld1  had  the  idea  to  nickel  plate  the  forms  before 
using  them,  being  convinced  that  traces  of  nickel  dissolve  in  acid 
copper  sulphate  solutions,  by  which  reaction  a  very  small  amount 
of  copper  is  separated  out  which  does  not  adhere  to  the  nickel 
surface;  so  that  by  further  electrolytic  precipitation  of  copper  it 
was  possible  to  obtain  a  precipitate  not  adherent  to  the  form  and 
easily  lifted  off. 

The  loosening  of  the  precipitate  is  easier  if  the  nickel  plated 
surface  is  treated  with  oxidizing  agents  or  soap-like  mixtures. 
In  the  latter  case  the  surface  of  the  form  becomes  extremely 
smooth  because  this  mixture  fills  up  any  small  unevennesses.  The 
oxidation  of  the  surface  of  the  form  can  be  produced  by  potas- 
sium chromate,  or  potassium  manganate  (the  solution  should  be 
concentrated).  The  forms  remain  in  this  solution  about  15  min- 
utes, and  are  then  washed  and  rubbed  off. 

Patent  Claim. 

The  process  for  manufacturing  easily  removable  metallic  pre- 
cipitates electrolytically,  consisting  in  providing  a  printing  plate 
of  any  suitable  form  with  a  coating  of  nickel,  or  using  plates  al- 
loyed with  nickel,  upon  which  the  metallic  precipitate  is  to  be  pro- 
duced ;  treating  these  plates  with  chromium  or  manganese  salts  or 
soap-like  mixtures  for  the  purpose  of  making  their  surfaces  per- 
fectly smooth,  whereby  the  easy  removal  of  the  metallic  precipi- 
tate is  rendered  possible  and  subsequent  polishing  may  be  dis- 
pensed with. 

METHOD  OF  HOLL. 

C.  Holl2  uses  pure  nickel  as  the  form  material  for  the  remov- 
able precipitates.  For  greater  cheapness  he  proposes  to  use  also 
the  following  materials :  cobalt,  copper,  steel,  lead,  cadmium,  an- 
timony, aluminium,  tin ;  also  ferro-silicon,  ferro-chrome,  etc.  The 
materials  used  can  also  be  supported  upon  glass  in  quite  thin 
sheets  and  casings.  Calcium  chloride,  also  oxygen,  either  atmos- 
pheric or  electrolytically  produced,  as  well  as  other  oxidizing  sub- 

1  German  Patent  SO.PCC,  Nov.  2?,  1888. 

2  German  Patent  7/,ccv,  Oct.  7,  ifg?.    Fupphrr.entz  ry  to  German    PaUnt  ,co,Fco,  NOT 
12,  iFSS. 


PRODUCTION  OF  UNIFORM  DEPOSITS  45 

stances,  render  possible  a  preparation  of  the  form  in  the  manner 
desired.  The  main  condition  is  always  that  the  intermediate  layer 
be  insoluble  in  the  electrolyte. 

For  instance,  cuprous  chloride,  CuCl,  can  be  used  in  copper 
baths  for  copper  cathodes,  silver  cyanide  for  silver  deposits  in 
silver  baths,  or  copper  forms  can  be  coated  with  a  thin  deposit  of 
silver  and  the  silver  coating  converted  into  a  compound,  with  a 
non-metal,  in  order  to  facilitate  the  detaching  of  the  subsequently 
precipitated  copper. 

Patent  Claims. 

1.  The  process  of  manufacturing  easily  removable  metallic  pre- 
cipitates   produced    galvanically    according    to    German    Patent 
50,890,  by  using  pure  nickel  for  the  printing  plate  or  form  in- 
stead of  a  nickel  coated  or  nickel  alloyed  plate. 

2.  In  the  use  of  the  process  of  German  Patent  50,890  and  the 
process  of  the  above  Claim  I,  the  treating  of  the  cathode  either 
with  various  oxidizing  agents  such  as  chromium  and  manganese 
solutions  or  also  with  hydrogen  peroxide,  ferricyanide  of  potas- 
sium, chloride  of  lime,  atmospheric  oxygen,  electrolytically  pro- 
duced oxygen  or  the  precipitation  of  oxides  insoluble  in  the  elec- 
trolyte, or  by  insoluble  conducting  metallic  cyanides,  haloids,  or 
sulphide  compounds  upon  the  surface  of  the  cathode  whereby  the 
electrolytic  deposition  of  the  metal  can  be  produced,  different 
from  the  metal  contained  in  the  protecting  intermediate  coating, 
or  the  metallic  surface  of  the  form. 

ELMORE'S  PROCESS. 

The  Elmore  German  and  Austro-Hungarian  Metal  Company1 
patented  in  the  year  1891  a  method  for  the  production  of  several 
consecutive  cylindrical  coatings  upon  a  mandril.  According  to 
this  process  the  metal  is  coated  in  place  with  a  material  which  pre- 
vents adhesion  of  the  subsequent  deposit,  such  as  fat,  metallic 
sulphides  and  the  like.  When  a  precipitate  has  been  formed  en 
this  the  insulating  process  is  repeated.  It  is  thus  possible  to  pro- 
duce several  layers  on  the  same  profile  upon  each  other,  and  by 
cutting  loose  or  otherwise  separating  from  each  other,  sheets,  rib- 
bons, etc.,  are  produced.2 

1  German  Patent  64.420.  July  7.  1891  ;  English  Patent  5,167,  March  23,  1891,  14,624,  (1890), 
11,778,  (i8S8)  ;  American  Patent  484.704  ;  French  Patent  214,641. 

2  Compare  also  Burgess,  Zeitschs.  f.  Electrochemie,  5,  334. 


46  MANUFACTURE   OF   METALLIC   OBJECTS 

Patent  Claim. 

The  process  of  producing  several  concentric  cylindrical  metal- 
lic precipitates  consecutively  on  a  mandril  electrolytically,  con- 
sisting in  coating  the  surface  of  an  already  formed  galvanic  pre- 
cipitate with  a  sulphide,  fat  or  other  material  preventing  the  ad- 
hesion of  a  new  precipitate  and  subsequently  precipitating  a 
further  galvanic  coating  upon  the  one  first  formed. 

NUSSBAUM'S  PROCESS. 

A  novel  method  of  separating  precipitates  from  the  forms  was 
proposed  and  patented  in  1896  by  A.  Nussbaum.1  The  process 
itself  will  be  further  described  at  length  and  I  limit  myself  here 
to  saying  that  the  easy  and  satisfactory  removal  of  the  precipitate 
from  the  particularly  constructed  model  is  obtained  by  introduc- 
ing a  fluid  under  pressure,  which  raises  a  valve-like  part  of  the 
surface  along  with  the  precipitate  upon  it  and  so  passes  between 
the  surface  of  the  form  and  the  precipitate. 

The  loosening  can  also  be  attained  by  depositing  the  metal  at  a 
free  space  upon  the  model  upon  a  bolt  so  arranged  that  it  can  be 
unscrewed  and  removed,  leaving  a  tube  which  serves  as  a  pres- 
sure tube  for  introducing  the  fluid  between  the  deposit  and  the 
mould. 

COLLAPSIBLE  FORMS. 

The  Electro-Metallurgical  Company,  Limited,2  uses  collapsible 
forms  from  which  the  deposit  is  easily  removed.  The  forms  con- 
sist of  thin  metallic  strips  rolled  in  many  windings  upon  each 
other.  The  loosening  of  the  deposit  is  produced  by  drawing  to- 
gether the  roll  of  strips  by  the  assistance  of  the  framework  in  the 
interior,  which  is  gripped  by  a  suitable  tool ;  that  is,  the  diameter 
of  the  successive  rolls  of  ribbon  are  diminished  and  the  precipi- 
tate becomes  loose  of  itself,  even  when  very  long  tubes  are  being 
produced. 

Because  of  its  elasticity,  the  form  after  being  removed  from  the 
precipitate  takes  its  original  shape  and  size. 

1  German  Patent  91,146,  May  28,  1896.    See  also  Zeitschrift  des  osterreischen  Ingenieur 
pnd  Architekten-Vereins,   1899,  296.   Engelhardt,   "  Ueber  das  Nussbaumsche  Ver- 
fahren." 

2  German  Patent  89,780,  May  24,  1896  ;  American  Patent  592,802  ;  English  Patent  11,338, 
May  23,  1896. 


UMiVERSlTY 

OF 


PRODUCTION  OF  UNIFORM  DEPOSITS  47 

Patent  Claim. 

The  cathode  for  the  reception  of  solid  precipitates  made  elastic 
and  spirally-formed  so  as  to  permit  being  rolled  together  and  thus 
loosened  from  the  precipitate  and  which  in  consequence  of  its  elas- 
ticity retakes  its  original  form. 

ELMORE'S  PROCESS. 

The  Elmore  German  and  Austro-Hungarian  Metal  Company1 
produces  objects  electrolytically,  and  uses  as  means  of  separating 
them  from  the  mandril  on  which  they  are  precipitated,  the  follow- 
ing process. 

The  thin  metallic  tubes  which  serve  as  mandrils  for  the  precipi- 
tation are  coated  over  with  a  material  fusible  at  a  low  tempera- 
ture and  made  smooth. 

Apparatus. 

The  mandril  a,  in  Fig.  10,  is  with  its  axle  a:  laid  in  a  socket 
b  of  the  frame  c.  The  projecting  part  of  the  frame  has  a  slit  d  in 


Fig.  10. 

which  are  two  boxes  e  adjustable  by  the  spindle  /.  In  the  boxes 
rest  the  spindle  of  the  roll  g  lying  parallel  to  the  mandril.  This 
roll  g  can  be  so  adjusted  by  the  spindle  f  that  it  forms  a  wedge- 
shaped  gutter  with  the  mandril  a,  into  which  by  means  of  the 
hopper-shaped  vessel  h,  the  material  is  fed  which  shall  be.  used 
to  coat  over  the  mandril.  The  spindle  a±  of  the  mandril  a  is  hol- 

i  German  Patent  63,838,  April  12,  1891  :    English  Patent  7,932,  May  22,  1900  ;   American 
Patent  485,919  ;  French  Patent  212,385. 


48  MANUFACTURE  OF  METALLIC  OBJECTS 

low  and  serves  for  the  introduction  and  circulation  of  cold  water ; 
on  the  other  hand,  either  hot  air  or  steam  is  led  through  the  roll 
g,  the  whole  arrangement  to  keep  the  mandril  cool  and  the  roll 
warm.  The  coating  material  coming  out  of  the  funnel  h  is  melt- 
ed by  the  heat  of  the  roll  g  and  sets  upon  the  cold  mandril  a.  The 
thickness  of  the  layer  produced  is  regulated  by  the  adjustment 
of  the  roll  g.  The  coating  may  be  either  of  an  easily  fusible 
metallic  alloy  or  of  some  wax-like  material.  In  the  latter  case, 
when  non-conducting  substances  are  brought  upon  the  mandril,  it 
is  necessary  to  puncture  the  coating  in  numerous  places  through 
to  the  metallic  surface  of  the  mandril ;  or  to  effect  this,  to  add  to 
the  coating  material  some  salt  easily  soluble  in  water  which  can 
be  washed  out  of  the  coating  by  immersion  in  water  before  plac- 
ing in  the  electrolyte  and  thereby  producing  the  desired  porosity 
of  the  coating.  The  coating  material  can  also  be  mixed  with 
graphite. 

When  the  electrolytically  produced  tube  has  been  deposited 
upon  the  mandril  the  whole  is  warmed,  as  for  instance,  by  intro- 
ducing hot  water  into  the  interior  of  the  mandril  and  so  melting 
the  coating  upon  it.  The  metal  shell  can  then  be  easily  removed 
from  the  mandril. 

Patent  Claims. 

1.  The  process  of  facilitating  the  loosening  of  electrolytically 
produced  deposits  from  a  tubular  mandril  consisting  in  giving  to 
the  latter  an  easily  fusible  or  smooth  coating,  soluble  in  a  fluid, 
by  the  use  of  a  rotating  smoothing  roll ;  in  case  the  coating  is  non- 
conducting, providing  it  with  numerous  small  holes,  or  mixing 
with  it  a  conducting  powder  or  a  powder  soluble  in  the  galvanic 
bath,  in  order  to  produce  a  conducting  path  between  the  mandril 
and  the  conducting  surface,  such  as  graphite  placed  upon  the  non- 
conducting coating. 

2.  In  the  application  of  the  process  of  Claim  I,  in  the  case  of 
using  a  coating  soluble  in  a  fluid  the  use  of  a  tubular  mandril 
provided  with  numerous  perforations  which  are  kept  closed  until 
the  finishing  of  the  perforated  tube  and  which  are  afterwards 
used  to  facilitate  the  solution  of  the  coating  in  a  short  time. 


PRODUCTION  OF  UNIFORM  DEPOSITS  49 

The  Best  Material  for  Coatings. 

P.  E.  Preschlin1  in  connection  with  the  Elmore  German  and 
Austro-Hungarian  Metal  Company  patents  as  particularly  ad- 
vantageous, the  filling  of  the  tubular  mandril  with  cold  water  in 
order  to  freeze  immediately  the  coating  placed  upon  it.  The  tube 
is  first  painted  with  asphalt  varnish  which  produces  a  good  ad- 
hesion of  the  coating.  The  latter  consists  of 

Paraffin  wax 75  parts 

Pitch 25     " 

This  melts  at  63°  C.  It  is  either  poured  upon  the  mandril  or  the 
cooled  mandril  is  rotated  while  dipping  into  the  melted  material. 
When  the  coating  has  set,  it  is  turned  off  smooth  by  the  use  of  a 
strong  jet  of  water.  In  this  manner  not  only  cylindrical  tubes, 
but  all  types  possessing  a  surface  of  revolution,  and  even  helical 
surfaces  can  be  made. 

Patent  Claim. 

In  the  use  of  the  process  of  patent  63,838  the  production  of  an 
easily  fusible  coating  upon  a  mandril  by  painting  the  latter  with 
asphalt  varnish  and  then  giving  it  a  coating  of  a  mixture  of  wax 
and  .pitch  with  simultaneous  cooling  of  its  interior. 

COLLAPSIBLE  MOULDS  OF  GERHARDI  &  CO. 

German  Patent  123.056,  of  December  13,  1900,  of  the  firm 
of  Gerhardi  &  Co.,  of  Ludenscheid,2  is  identical  with  the  Stein- 
weg  process  and  recalls  that  of  the  Electro-Metallurgical  Com- 
pany, Limited.  It  is  concerned  with  the  manufacture  of  easily  de- 
tachable galvanic  precipitates  and  especially  with  the  manufacture 
•of  nickel  vessels. 

Objects  of  Pure  Nickel. 

The  previous  processes  for  the  separating  of  galvanic  precipi- 
tates from  their  matrices  are  very  little  suited  in  many  .cases  for 
nickel  deposits ;  in  some  cases  quite  impracticable,  especially  when 
ihe  precipitate  is  made  upon  a  surface  which  is  not  quite  even  or 
aipon  a  grooved  or  recessed  matrix. 

In  depositing  nickel  the  ordinarily  used  matrices  of  wax,  rub- 

1  German  Patent  72,195,  April  6,  1893. 

•2  English  Patent  13,365,  1901,  and  German  Patent,  March  17,  1901 


50  MANUFACTURE:  OF  METALLIC  OBJECTS 

her,  gum  arabic,  and  similar  materials  made  superficially  conduct- 
ing, are  impracticable  since  heavy  deposits  in  a  reasonable  time 
can  only  be  obtained  in  hot  solutions  in  which  the  materials  named 
above  would  become  soft  and  lose  their  form. 

The  process  of  making  the  forms  out  of  easily  fusible  metal 
and  melting  the  latter  out  after  the  formation  of  the  deposit  has 
the  great  disadvantage  of  always  forming  an  alloy  with  the  first 
precipitated  part  of  the  deposit. 

It  is  only  possible  in  depositing  nickel  to  use  matrices  of  hard 
metal  such  as  brass,  copper  or  iron.  Using  such  materials,  only 
simple  shaped  flat  objects  or  smooth  hollow  objects  like  cylindri- 
cal and  conical  objects  can  be  made,  or  such  as  allow  the  removal 
of  the  core  either  by  the  contraction  of  the  same  or  by  the  ex- 
panding of  the  precipitate  by  means  of  rolling,  hammering,  water 
pressure,  etc. 

The  process  is,  on  the  other  hand,  not  applicable  for  all  other 
objects ;  that  is,  for  the  production  of  hollow  vessels  with  con- 
stricted openings,  recesses  or  oil-sets  or  ornamental  decorations. 

Process. 

The  process  to  be  described  allows  of  the  production  of  articles 
of  any  form  whatever,  and  in  particular,  of  hollow  vessels  of  al- 
most any  desired  form  and  with  raised  or  recessed  surfaces.  The 
manner  of  working  is  characterized  by  the  use  of  thin  walled  hol- 
low metallic  matrices  made  out  of  soft  easily  torn  metals ;  for  in- 
stance, of  alloys  of  tin,  zinc,  or  lead  with  antimony,  bismuth,  cad- 
mium, arsenic,  mercury,  etc.,  the  brittleness  of  which  is  increased 
when  the  temperature  is  made  very  low  (using  tin  or  tin-antimony 
alloys),  or  when  the  temperature  is  raised  (as  with  tin,  lead  or 
bismuth  alloys)  ;  and  the  side  which  does  not  receive  the  precipi- 
tate is  provided  with  grooves  or  small  linear  recesses.  The  grooves 
which  reach  nearly  through  to  the  other  surface  divide  the  walls 
into  strips  or  divisions.  After  the  formation  of  the  precipitate, 
the  single  strips  are  lifted  and  torn  away  by  the  aid  of  suitable 
tools.  By  properly  dividing  up  the  walls  of  the  matrices  in  this 
manner,  cores  of  almost  any  shape  whatever  are  easily  removed 
without  changing  the  form  of  the  precipitate. 

The  carrying  out  of  the  process  may  be  varied  in  separate 


PRODUCTION  OF  UNIFORM  DKPOSITS  51 

cases.  The  material  for  the  matrices  is  lead,  tin,  or  an  alloy,  such 
as  Britannia  metal,  as  best  suited  to  the  purpose. 

If  the  matrix  is  made  of  sheet  metal,  the  sheet  may  be  previous- 
ly passed  between  rolls,  one  of  which  is  smooth  and  the  other  pro- 
vided with  grooves  and  projections  or  the  plate  is  laid  upon  a 
steel  plate  provided  with  corresponding  projections,  and  the  two 
passed  together  between  two  smooth  rolls.  With  cast  matrices, 
these  grooves  may  be  easily  produced  by  providing  the  part  of  the 
mould  which  is  back  of  the  matrix  with  corresponding  ribs  or 
projections  or  the  corrugations  may  be  made  by  cutting  by  a 
suitable  tool  upon  a  lathe,  a  planing  or  a  milling  machine,  or  final- 
ly done  by  hand.  In  this  case  care  must  be  taken  that  the  tool 
does  not  cut  too  deeply  so  as  not  to  damage  the  other  side  of  the 
matrix. 

The  cuts  or  grooves  can  be  made  either  before  or  after  the  for- 
mation of  the  precipitate.  The  direction  of  the  grooves  is  pre- 
ferably so  ordered  that  the  walls  of  the  matrix  are  divided  into 
single  parallel  strips  which  can  easily  be  torn  away.  With  ob- 
jects of  revolution  it  is  often  practicable  to  produce  the  grooves 
spirally  so  that  the  whole  wall  of  the  form  can  be  rolled  off  in  a 
single  helicoidal  strip.  With  complex  matrices  a  further  sub- 
division of  the  walls  must  sometimes  be  made.1 

1  See  also  Zeitschr.  f.  Rlektrochemie,  8,  193. 


VIII.     MANUFACTURE   OF   METALLIC    POW- 
DERS AND  THE  LIKE. 


In  order  to  produce  directly  metallic  powders  electrolytically 
there  are  two  methods.  It  may  be  separated  out  cathodically  from 
such  solutions  which  do  no  furnish  coherent  precipitates,  or  it. 
may  be  separated  out  of  a  normal  metallic  bath  by  precipitation 
upon  a  powdered  cathode.  The  latter  method  must  really  be  in- 
cluded in  the  art  of  galvanoplasty  since  it  concerns  a  superficial 
coating  of  a  conducting  substance. 

PRINCIPLES. 

If  powder  is  to  be  separated  directly  from  a  solution  of  metallic 
salt,  dilute  solutions  are  used  or  such  additions  are  made  to  the 
electrolyte  as  experience  has  shown  will  cause  the  separation  of 
the  metal  in  the  form  of  a  powder.  Such  additions  may  be,  for  in- 
stance, solutions  of  such  metals  which  are  more  electropositive 
than  the  metal  to  be  precipitated  or  a  corresponding  quantity  of 
free  acid. 

LEAD   POWDER. 

A  fine  crystalline  powder  of  lead  can  be  obtained  from  a  solu- 
tion of  lead  nitrate  containing  50  grams  of  lead  nitrate  per  liter 
if  care  is  taken  to  keep  the  current  density  above  one  ampere  per 
square  decimeter  of  depositing  surface.  It  is  also  important  that 
the  electrolyte  be  actively  stirred,  otherwise  layers  of  solution 
rich  in  metal  form  at  the  bottom  of  the  vessel  from  which  lead  is 
precipitated  in  another  form. 

COPPER  POWDER. 

A  strongly  acid,  quite  dilute  soltion  of  copper  sulphate  furnish- 
ed copper  in  the  form  of  a  fine  powder.  The  Elektrizitats-Aktien- 
gesellschaft,  formerly  Schuckert  &  Company,1  produce  in  this 
manner,  and  afterwards  still  further  pulverize  the  powder  accord- 
ing to  the  German  Patent,  No.  88,415,  of  August  15,  1896. 

i  German  Patent  88,273,  Aug.  24,  1894  ;  Peters  "  Elektrometallurgie  und  Galvanoplas- 
tik,  '  I,  47  et  seq.  and  Zeitschr.  f.  Rlektrochemie,  3,  199. 


MANUFACTURE  OF  METAUJC  POWDERS  53 

Principle. 

The  primary  condition  is  that  a  crystalline  deposit  always  falls 
if  compounds  of  higher  valence  are  present  in  the  electrolyte, 
which  by  reduction  to  lower  valence,  partly  redissolve  the  metal 
precipitated. 

Example. 

Tin  may  be  obtained  as  a  fine  powder  if  ferric  chloride  or  ferric 
sulphate  is  added  to  the  electrolyte  along  with  small  quantities  of 
organic  acids.  The  metal  of  these  solutions  added  should  not  be 
precipitated  by  the  current,  which  is  easily  effected  by  keeping  the 
solutions  correspondingly  acid  or  alkaline  according  to  the  kind 
of  metal  in  the  solution  added.  Copper  powder  may  be  precipi- 
tated from  cuprous  chloride  solutions  if  cupric  chloride  or  ferric 
chloride  is  added  continuously  during  the  electrolysis. 

In  case  that  the  metallic  salt  added  is  only  raised  to  the  higher 
state  of  oxidation  during  electrolysis,  the  current  density  at  the 
anode  is  so  regulated  that  as  the  anode  is  being  dissolved  some  of 
the  added  salt  is  simultaneously  somewhat  oxidized  or  perduced. 

Process. 

The  baths  used  are  worked  with  an  average  tension  of  0.8 
volt  and  a  current  density  of  220  amperes  per  square  meter,  the 
distance  betwen  the  electrodes  10  centimeters.  The  solution  is 
kept  at  room  temperature  and  agitated  by  a  stirring  apparatus. 
When  making  a  loosely  crystalline  mass  of  metallic  copper,  there 
are  used  anodes  of  cast  copper  20  millimeters  thick  and  cathodes 
of  sheet  copper  i  millimeter  thick. 

Uses. 

According  to  the  Austrian  Schuckert  Works,  this  product  is 
capable  of  replacing  bronze  powder  made  in  the  ordinary  way. 
Although  the  product  is  quantitatively  satisfactory,  it  is,  however, 
too  heavy  to  compete  with  the  ordinary  bronzes.  On  this  ground, 
no  plant  has  been  erected  for  the  carrying  out  of  the  operation. 

Patent:  Claim. 

The  process  for  the  production  of  loosely  coherent  crystalline 
metallic  masses  suitable  for  the  manufacture  of  metallic  scales  or 


54 


MANUFACTURE  OF  METALLIC  OBJECTS 


bronze  powder,  electrolytically,  consisting  in  using  as  electrolyte 
solutions  containing  the  metal  to  be  precipitated  and  also  other 
metals  which  are  not  to  be  precipitated  and  which  are  in  the  high- 
er state  of  oxidation,  and  which  are  able  to  redissolve  the  pre- 
cipitating metal  forming  its  lower  salts ;  the  anode  being  soluble 
and  of  the  same  material  as  that  being  precipitated,  and  no  dia- 
phragm being  used  in  the  process. 

PROCESS  OF  THE  SOCIETE  CIVILE. 

The  Societe1  civile  d'etudes  du  Syndicat  de  1'acier  Gerard  sub- 
jects the  metal  to  the  action  of  the  current  while  in  the  molten 
condition  and  in  a  thin  freely  falling  column  using  high  current 
densities  and  small  tensions. 

Applications. 

The  process  is  suitable  for  the  manufacture  of  metallic  powders 
and  also  as  an  intermediate  step  in  a  process  having  for  its  object 


Fig.  ii. 

the  subdivision  of  material  without  reference  to  its  state  of 
comminution  or  the  final  condition.  The  first  use  is  illustrated  by 
the  production  of  lead  powder  for  accumulator  plates.  The  second 
method  of  application  may  be  illustrated  by  the  treatment  of  a 
finely  divided  stream  of  fluid  iron  with  an  excess  of  air  for  the 
production  of  steel. 

The  apparatus  used  is  shown  in  Fig.  n. 

1  German  Patent  89,062,  Dec.  14,  1895  ;  see  also  Zeitschrift  f.  Elektrochemie,  3,  227. 


MANUFACTURE  OF   METALLIC   POWDERS  55 

The  melted  metal  is  in  the  vessel  a,  in  the  upper  part  of  the 
shaft  s  terminating  below  in  the  vertical  middle  plane  of  the  shaft 
in  a  slit-like  opening  a^.  At  some  distance  below  the  latter  the 
electrodes  ee,  most  suitably  of  carbon,  project  through  the  walls 
of  the  shaft,  leaving  between  their  parallel  sides  an  opening  cor- 
responding to  the  above  mentioned  slit.  The  metal  falls  in  a  thin 
layer  between  the  electrodes  ee,  is  thereby  finely  divided  by  the 
current,  its  temperature  is  raised,  and  it  falls  as  a  rain  m2  in  the 
lower  part  of  the  shaft  where  it  collects  as  a  powder  or  dust  ac- 
cording to  whether  the  particles  fall  a  long  distance,  or  the  bot- 
tom of  the  shaft  is  artificially  cooled,  or  the  arrangement  of  a  re- 
ceiving fluid  which  may  be  placed  in  the  bottom  of  the  shaft,  or 
a  current  of  ascending  gas  which  may  be  projected  against  it. 

In  case  the  transformation  to  powder  or  dust  is  only  an  in- 
termediate step  in  the  production  of  the  material,  in  order  to 
allow  of  the  better  action  of  a  vaporized  or  gaseous  reagent,  for 
instance  such  as  the  steel  manufacturing  process  mentioned  above, 
the  shaft  may  be  provided  at  the  proper  distance  below  the  elec- 
trodes with  tuyeres  for  the  introduction  of  the  reagents;  and 
higher  up  and  closer  to  the  electrodes,  with  openings  d  for  the 
exit  of  the  same  or  of  the  gaseous  products  resulting.  ( See  Fig. 
n,  right  hand  side). 

PROCESS  OF  HOEPFNER. 

L.  Hopfner1  obtains  loose  metallic  masses  in  coherent  flat 
plates.  He  first  precipitates  from  the  solution  which  may  be  of 
normal  composition  a  pulverized  or  moss-like  branching  metallic 
mass  by  using  high  current  density  and  for  a  period  of  15  to  30 
minutes,  and  then  somewhat  stiffens  this  by  using  a  smaller  cur- 
rent density  for  several  hours  and  coats  them  with  a  coherent  me- 
tallic plating. 

Porous  Copper. 

In  orcler  to  make  porous  copper,  the  ordinary  acid  copper  bath 
used  in  galvanoplasty  can  be  employed.  Starting  with  a  high 
current  density  of  same,  4  amperes  per  square  decimeter,  powder- 
ed copper  is  as  is  well-known  obtained;  this  is  followed  by  ai 

1  German  Patent  87,430,  May  n,  1895;  English  Patent  17,671,  Aug.   10,  1896;  see  also 
Zeitschrift  f.  Elektrochemie,  3,  130. 


$6  MANUFACTURE  OF  METALLIC  OBJECTS 

smaller  current  density,  which  is  continued  until  the  dark  color  of 
the  powdered  precipitate  is  changed  into  the  well-known  bright 
red  color  of  electrolytic  copper.  If  it  is  wished  to  work  entirely 
with  small  current  densities,  a  solution  is  used  which  contains  less 
copper  and  more  sulphuric  acid. 

Porous  Lead. 

Lead  can  be  similarly  obtained,  but  it  is  better  to  throw  down 
the  lead  not  in  the  state  of  powder,  but  in  the  form  of  leafy  or 
moss-like  crystals.  The  suitable  current  density  for  obtaining 
these  leaves  may  vary  between  that  which  produces  spongy  lead 
and  that  which  produces  dense  lead.  This  current  is  allowed  to 
run  for  some  time,  then  the  current  density  is  decreased  some- 
what in  order  to  make  the  small  leaves  which  are  at  first  some- 
what delicate  more  resistant.  The  regulating  of  the  current  den- 
sity (from  the  stronger  to  the  feebler)  can  be  automatically  ad- 
justed by  using  at  first  a  current  density  only  a  little  greater  than 
that  necessary  to  deposit  metallic  powder  or  leafy  lead ;  as  soon 
as  a  certain  quantity  of  metal  has  thus  separated,  the  total  cathode 
surface  in  contact  with  the  electrolyte  being  increased,  the  new 
surface  receives  deposit  with  a  lower  current  density,  if  the  total 
current  has  been  kept  constant.  For  the  production  of  the  subse- 
quent layers  of  metal  successively  higher  current  densities  must 
be  used.  It  is  to  be  recommended  to  exert  a  small  pressure  upon 
the  mass  of  leaf-like  lead  by  means  of  a  smooth  surface,  in  order 
to  reduce  any  large  cavities  and  to  obtain  a  uniform  porous  de- 
posit. Not  all  lead  solutions  are  equally  well  suited  for  the  ob- 
taining of  such  leaf-like  lead.  A  solution  of  nitrate  of  lead  gives 
for  instance  hard  leaves  which  become  brittle  when  pressed  to- 
gether, while  a  solution  of  lead  oxide  in  caustic  soda  or  caustic 
potash  yields  very  soft  and  flexible  leaves. 

Patent  Claims. 

1.  The  process  for  the  electrolytic  production  of  metals  in  the 
state  of  a  porous  but  coherent  precipitate,  characterized  by  the 
consecutive  use  of  difTering  current  densities  by  which  a  pow- 
dery or  leaf-like  or  branching-mossy  form  of  metal  is  first  pre- 
cipitated and  afterwards  dense  metal. 

2.  In  the  process  of  Claim  i,  the  automatic  regulation  of  the 


MANUFACTURE  OF   METALLIC   POWDERS  57 

current  density  by  the  use  of  an  original  current  density  only 
slightly  above  the  limit  of  that  which  furnishes  dense  metal. 

3.  In  the  production  of  the   leaf-like   structure   of  metals   as 
claimed  in  the  process  above  described,  the  compressing  of  the 
electrolytically  produced  metallic  leaves  by  a  gentle  mechanical 
pressure  not  sufficient  to  affect  the  porosity,  used  alternately  with 
the  application  of  the  current. 

4.  In  the  process  of  Claims  i,  2  and  3,  the  use  of  a  solution  of 
lead  oxide  in  caustic  alkali  as  an  electrolyte. 

Modification  of  the  Process. 

Instead  of  changing  the  current  density  and  using  the  same 
concentration  of  solution  the  former  may  be  kept  constant  and 
the  latter  changed,1  or  to  increase  the  effect  both  factors  may  be 
changed  at  once;  for  instance,  a  loose  form  of  metal  obtained  by 
the  use  of  a  high  current  density  and  a  low  concentration  of  the 
electrolyte,  and  for  producing  dense  metal  high  concentration 
with  a  suitable  current  density.  Increasing  the  temperature  acts 
upon  the  electrolyte  in  the  same  way  as  increasing  the  concentra- 
tion. The  best  work  is  done  in  general  by  using  for  the  deposition 
of  loose  metal  the  high  current  density  at  a  low  temperature  and 
with  a  small  concentration  of  the  bath  ;  and  for  dense  metal  higher 
temperatures,  greater  concentration  and  a  suitable  current  den- 
sity. Agitation  of  the  electrolyte  at  the  cathode  or  movement  of 
the  cathode  itself  acts  similarly  to  increase  of  concentration  or  of 
temperature ;  agitation  of  the  electrolyte  permits  of  the  deposition 
of  dense  metal. 

Agitation  acts  therefore  like  concentration,  particularly  since 
it  equalizes  the  dilution  at  the  cathode  because  of  the  deposition 
of  the  metal  from  the  solution.  Its  action  is  particularly  to  be 
noted  when  the  electrolyte  is  agitated  in  order  to  reduce  the  polar- 
ization at  the  anode.  Finally  under  quite  similar  conditions  a 
change  in  the  metallic  deposit  may  be  attained  by  putting  the 
cathodes  alternately  into  baths  of  qualitatively  different  composi- 
tion ;  for  instance,  in  the  production  of  porous  copper  alternately 
in  baths  which  are  neutral  or  acidified  by  sulphuric  acid,  or  for 
increasing  these  effects  a  change  in  the  qualitative  composition  of 

1  German  Patent  89,289,  Jan.  i,  1896  ;  Addition  to  German  Patent,  87.430. 


58  MANUFACTURE  OF  METALLIC  OBJECTS 

the  bath  may  be  coupled  with  changes  in  the  current  density,  con- 
centration, temperature  or  by  decreasing  agitation  so  that  there  is 
obtained  first  loose  and  then  dense  metal.  To  carry  out  regularly 
the  alternations  of  the  conditions  named  two  different  systems 
may  be  advanced>  either  the  use  of  two  separate  cells  and  two 
separate  electrolytes  in  which  the  cathodes  are  alternately  plunged 
or  working  always  in  the  same  cell  by  changing  the  current  den- 
sity, temperature  and  agitation  as  well  as  also  circulating  through 
it  fluids  of  differing  concentrations  and  differing  compositions. 

It  is  recommended  to  combine  both^systems  so  that  the  loose  de- 
posit is  treated  in  one  cell  first  with  a  somewhat  lower  current 
density  or  slightly  raised  temperature  until  it  becomes  so  strong 
that  it  will  bear  transporting  to  another  cell  where  it  will  be  still 
further  strengthened.  Since  the  surface  of  the  cathode  contin- 
ually increases  during  the  electrolytic  process,  a  change  from 
loose  to  dense  metallic  deposit  can  be  allowed  to  proceed  auto- 
matically if  the  conditions  for  obtaining  the  loose  metal  deposit  are 
arranged  at  the  beginning,  as  near  as  possible  to  the  conditions 
necessary  for  the  formation  of  dense  metal.  Now  with  a  change 
of  current  strength,  the  change  in  temperature  is  particularly  ad- 
vantageous for  the  automatic  regulation  for  the  change  in  struc- 
ture in  the  metallic  deposit.  It  is  to  be  recommended  to  particu- 
larly use  a  gentle  pressure  not  injurious  to  the  porosity  of  the 
metal.  The  process  of  patent  87,430  may  be  cheapened  by  the 
additional  means  proposed,  namely  of  using  agitation  of  the  elec- 
trolyte and  higher  temperatures  thereby  producing  also  a  very 
active  depolarization  of  the  anode.  In  fact,  in  for  example,  the 
separation  of  lead  from  not  too  dilute  solutions  of  lead  oxide  in 
caustic  alkalies,  the  anode  remains  permanently  a  metallic  white, 
even  with  current  densities  of  200  amperes  per  square  meter  if 
high  temperatures  are  used.  Using  high  temperatures,  the  refin- 
ing of  the  metal  is  much  facilitated  and  cheapened  since  in  conse- 
quence of  the  smaller  bath  tension  the  less  electropositive  metals 
do  not  go  into  solution.  On  the  other  hand,  low  temperatures  are 
suited  for  the  production  of  insoluble  oxides  and  peroxides  upon 
the  anode.  For  example,  extensive  investigations  down  at  a  tem- 
perature of  9°  C.  showed  that  the  anodes  coat  themselves  over 


MANUFACTURE:  OF  METALLIC  POWDERS  59 

with  undissolved  or  insoluble  oxides  more  quickly  the  lower  the 
temperature. 

Patent  Claims. 

Hopfner  protects  his  process  by  the  following  comprehensive 
claims. 

1 .  The  method  of  carrying  out  the  process  of  patent  87,430  for 
the  electrolytic  production  of  metals  in  the  from  of  porous,  yet 
coherent  precipitates,  characterized  a)  by  alternate  application  of 
two  solutions  of  different  concentrations  and  such  changes  of  the 
suitable  current  density  in  each  case  that  at  one  concentration 
loose  metal,  at  the  other  concentration,  dense  metal  is  precipi- 
tated; or  b)  by  the  alternate  application  of  two  different  tempera- 
tures of  the  electrolyte  and  such  changes  of  the  corresponding 
current  density  that  at  one  temperature  loose  and  at  the  other  tem- 
perature dense  metal  precipitates;  or  c)  by  the  alternate  applica- 
tion of  rest  and  motion  to  the  cathode  or  to  the  fluid  at  the  cathode 
and  such  changes  of  the  corresponding  current  density  that  in  the 
one  case  loose  metal  and  in  the  other  case  dense  metal  is  obtained  ; 
or  d)  by  the  alternate  application  of  two  differently  constituted 
baths  and  such  changes  of  the  current  density  that  in  the  one  bath 
the  precipitated  metal  is  loose  and  in  the  other  is  of  a  dense  struc- 
ture; or  e)  by  the  alternate  application  of  two  of  the  above  de- 
scribed combinations  included  under  the  headings  a)  to  d),  and 
using  suitable  current  densities  so  that  with  one  combination  loose 
metal  and  with  the  other  combination  dense  metal  is  precipitated. 

2.  For  the  application  of  the  process  of  Claim  I,  a)  to  e)  the 
separate  and  combined  application  of  the  two  following  systems; 
a)  the  alternate  introduction  of  the  cathode  into  separate  cells  in 
which  the  arrangements  according  to  Claim  i,  a)  to  e)   are  so 
adjusted  that  the  cathode  in  the  one  cell  is  coated  with  loosely  co- 
herent metal  and  in  the  other  with  dense  metal;  b)  the  maintain- 
ing of  the  cathodes  in  the  same  cell  in  which,  however,  the  current 
density,  temperature,  agitation  or  the  presence  of  different  elec- 
trolytes  (the  latter  by  circulation)   are  made  to  regularly  alter- 
nate. 

3.  In  the  process  of  Claim  i,  a)  to  e)  the  automatic  regulation 
of  the  passage  of  the  loose  metal  into  the  dense  metal  by  the  suit- 


60  MANUFACTURE  OF  METALLIC  OBJECTS 

able  utilization  of  the  automatically  increasing  surface  of  the  ca- 
thode and  the  diminution  of  the  current  density  produced  thereby. 

4.  In  the  process  of  Claim  i,  a)  to  e)  and  2,  b)  :  the  use  of  ar- 
rangements for  the  automatic  regulation  of  the  temperature  and 
the  current  strength. 

5.  In  the  process  of  Claims  i  to  4,  the  application  of  a  gentle 
pressure  not  injurious  to  the  porosity  of  the  metallic  precipitate, 
used  alternately  with  the  action  of  the  current. 

6.  In  the  process  of  Claims  i  to  5,  the  application  of  a  solution 
of  lead  oxide  in  a  caustic  alkali  as  an  electrolyte. 

7.  In  the  electrolysis  of  dilute  metallic  compounds  according  to 
the  processes  described  in  Claim  i,  a)  to  e),  the  use  of  impure 
metal  as  anodes  for  the  purpose  of  refining  it  and  the  utilization 
of  the  oxides  formed  at  the  anode  for  the  obtaining  of  by-pro- 
ducts. 

PROCESS  OF  HUBER  AND  SACHS, 

Huber  and  J.  Sachs1  produce  metallic  or  metallized  powder  as  a 
substitute  for  metallic  and  bronze  colors,  by  precipitating  the  de- 
sired metal  upon  a  core  consisting  of  a  conductor  of  the  first 
class.  The  powdered  cathode  to  be  coated  is  agitated  in  the  bot- 
tom of  the  electrolytic  vessel  in  contact  with  a  solid  cathode  con- 
ductor so  that  an  intimate  contact  of  the  powder  with  the  cathode 
conductor  is  assured  with  a  continuously  changing  position  of  the 
particles.  The  anodes  are  parallel  to  the  cathode  plate  and  are 
separated  from  them  by  a  clay  diaphragm  in  order  to  avoid  short 
circuits  between  the  anode  and  the  powdered  metal  in  suspension. 

Patent  Claim. 

The  process  for  the  manufacture  of  metallic  powder  consisting 
in  the  electrolytic  formation  of  a  metallic  coating  upon  a  conduct- 
ing powder  which  is  kept  in  motion  in  a  bath  in  such  a  manner  as 
to  be  in  contact  with  the  cathode  while  contact  with  the  anode  is 
prevented  by  means  of  a  diaphragm. 

1  German  Patent  79,896,  June  27,  1894;  American  Patent  521,991  and  521.992,  June  26, 
1894  ;  American  Patent  522,415,  July  3,  1894. 


IX.    MANUFACTURE  OF  METALLIC  FOIL. 


In  order  to  produce  metallic  foil  or  thin  sheets  electrolytically, 
particularly  prepared  cathode  sheets  are. usually  hung  opposite  to 
anodes  of  the  metal  to  be  precipitated  in  a  suitable  electrolyte  and 
left  there  until  the  desired  thickness  is  reached. 

PROCESS  OF  REINFELD. 

A.  K.  Reinfeld1  pastes  paper  upon  the  thin  copper  sheet  pro- 
•duced  in  the  above  manner  and  tears  it  away  from  its  support. 
Reinfeld  uses  as  cathode  nickel-plated  sheets  which  have  been 
treated  with  oxidizing  agents  or  soap-like  materials  in  order  to 
prevent  the  adhesion  of  the  copper  skin.  In  this  manner  prepared 
sheets  of  only  i  to  2  thousandths  of  a  millimeter  thickness  are  ob- 
tained. 

Operation. 

The  well-nickeled  and  polished  cathode  is  allowed  to  stand  a 
quarter  of  an  hour  in  a  concentrated  solution  of  potassium  chro- 
mate  or  potassium  manganate  and  is  then  rubbed  off.  The  plates 
are  covered  on  both  sides  with  metal  and  the  foil  is  obtained  from 
the  cathodes  with  a  polish. 

PROCESS  OF  ENDRUWEIT. 

C.  Endruweit2  makes  copper  and  nickel  foil  by  titrating  the 
metal  plate  serving  as  a  form  with  a  concentrated  solution  of  an 
alkaline  sulphide,  and  after  washing  off  with  water  dips  it  in  di- 
lute caustic  soda  solution.  It  is  then  again  washed  off  and  placed 
in  the  metal  bath.  Under  some  circumstances,  it  is  recommended 
to  have  the  plates  connected  as  cathodes  with  a  source  of  current 
when  they  are  dipped  into  the  caustic  soda  solution. 

Patent  Claims. 

i.  The  process  for  the  preparation  of  metallic  plates  upon 
-which  an  insoluble  skin  of  metal  is  to  be  precipitated  in  order  to 

'  English  Patent  3.222,  Feb.  22,  1889. 

2  English  Patent  2.724,   Feb.  7,   1893  ;  German  Patent  82,664,  Jan.  25,  1895.     See  also 
Jahrbuch,  2,  194. 


62 


MANUFACTURE  OF  METALLIC  OBJECTS 


manufacture  metallic  paper,  consisting  in  treating  the  plate  first 
with  a  solution  of  alkaline  sulphide  in  water  and  immediately  af- 
terwards with  a  solution  of  caustic  alkali. 


Fig.    12. 

2.  A  special  method  of  carrying  out  the  process  of  Claim   I, 
especially  suitable  for  plates  upon  which  a  skin  of  copper  is  to  be 


MANUFACTURE  OF   METALLIC  FOIL  63 

precipitated,  consisting  in  connecting  the  plates  as  negative  elec- 
trodes short-circuited  to  suitable  anodes  while  being  dipped  in  the 
caustic  alkali  solution. 

Improvements. 

Endruweit  has  arranged  the  process  in  such  manner1  as  not  to 
use  a  metallic  plate  as  cathode  but  an  endless  metallic  band  (see 
Fig.  12). 

The  metallic  band  M  passes  in  series  through  the  roll  R,  the 
polishing  roll  P,  passes  then  into  the  vessel  G  in  which  it  is  pre- 
pared by  a  5  per  cent,  solution  of  alkaline  sulphide.  It  then  passes 
into  the  cleaning  arrangement  A,  and  thence  into  the  nickeling 
bath  Ni,  where  a  thin  film  of  nickel  is  deposited  upon  it,  which 
as  has  already  been  explained,  serves  very  well  as  an  intermedi- 
ate deposit.  The  copper  bath  Cu  must  self-evidently  be  of  larger 
dimensions  because  the  real  precipitate  is  there  given.  Past  the 
bath  Cu  there  is  a  washing  arrangement  which  frees  the  precipi- 
tate from  electrolyte  coming  over  from  the  last  bath. 

The  backing  paper  which  is  rolled  off  from  the  spool  Px  by 
means  of  rollers  is  supplied  continuously  with  the  necessary  paste 
from  the  holder  K  which  distributes  paste  upon  the  precipitate. 
The  pasted  metallic  band  passes  now  to  a  steam  drying  apparatus 
D,  and  afterwards  the  finished  metallic  paper  is  stripped  from  the 
metallic  band  by  a  sharp  instrument  and  rolled  up  upon  P2. 

ELMORE'S  PROCESS. 

Elmore's  process  of  producing  metallic  sheets  electrolytically 
by  the  production  of  a  non-metallic  intermediate  coating  has  been 
already  described  on  page  47  and  is  merely  referred  to  here. 

DESSOLLE'S  PROCESS. 

L.  E.  Dessolle2  produces  lead  metal  and  all  kinds  of  useful  ob- 
jects which  are  to  be  obtained  polished  from  the  moulds,  by  satu- 
rating the  surface  of  the  metallic  form  with  hydrogen.  The  form 
is  first  provided  with  a  coating  which  is  indifferent  towards  the 
electrolyte,  and  which  is  not  quite  removed  by  the  hydrogen. 
Acids  or  alkalies  may  be  used  as  electrolyte  and  anodes  which  are 

1  American  Patent  676,357  ;  see  also  Zeitschr.  f.  Elektrochemie,  8,  99. 

2  German  Patent  98,468,  Aug.  12,  1897.     See  Jahrbuch,  6,  333. 


. 


64  MANUFACTURE:  OP  METALLIC  OBJECTS 

insoluble  in  the  electrolyte.    A  voltage  of  2.5  to  3  volts  is  used  and 
the  preparing  operation  lasts  up  to  three  hours. 

Patent  Claim. 

The  process  for  the  preparation  of  cathodes  for  the  immediate 
production  of  polished  metallic  sheets  or  other  objects  electrolyti- 
cally,  by  placing  upon  the  cathode  a  coating  not  soluble  in  the 
electrolytic  bath,  then  saturating  this  coating  in  the  electrolytic 
bath  described  with  hydrogen  and  then  polishing. 

PROCESS  OF  COWPER-COLES. 

The  process  similar  to  that  of  Elmore  (see  page  45)  was 
patented  by  Cowper-Coles  in  England  in  1899,  No.  16,210.  The 
latter  produces  several  concentric  layers  upon  each  other,  and 
uses  as  an  intermediate  coating  in  order  to  facilitate  detaching 
the  deposit,  an  alcoholic  solution  of  wax  or  a  layer  of  metallic 
oxides  or  sulphides.  The  layer  of  oxide  is  obtained  by  heating  in 
a  mixture  of  air  and  steam,  the  sulphide  layer  by  dipping  into 
potassium  sulphide.  Cylindrical  brass  forms  are  used  as  cathodes 
which  are  rotated  mechanically  at  a  surface  speed  of  1,000  feet 
per  minute.  The  precipitate  comes  down  in  this  manner  bright 
and  coherent,  although  quite  extraordinary  current  densities  are 
used. 

After  several  superimposed  metallic  sheets  have  been  deposited, 

separated  from  each  other  by  layers  of  wax  or  metallic  sulphides, 

the  whole  is  cut  through  parallel  to  the  axis  of  the  cylinder  and 

the  metallic  sheets  are  separated  from  each  other.     The  copper 

.  foil  thus  produced  is  used  especially  for  making  dynamo  brushes. 

PROCESS  OF  LANDAUER  &  CO. 

As  an  example  of  one  of  the  processes  which  are  used  on  a  large 
scale  for  the  manufacture  of  metallic  paper,  that  of  Landauer1 
may  be  described.  In  Landauer  &  Company's  Galvanic  Metal 
Paper  Works  in  Vienna  there  is  manufactured  paper  pasted  to- 
copper  foil  or  nickel  plated  copper  foil,  as  also  other  similar 
manufactures  which  are  protected  by  a  number  of  patents. 
Among  the  latter  may  be  mentioned  copper  brushes  for  dynamos, 
coppered  asbestos  gaskets,  flanged  gaskets  consisting  of  asbestos, 
with  a  loose  copper  coating,  etc. 

i  English  Patent  15,573,  July  15,  1898. 


MANUFACTURE  OF  METALLIC  FOIL  65 

Principle. 

earthen-ware  i  meter  long,  50  centimeters  wide  and  70  centi- 
Landauer  precipitates  copper,  or  first  nickel,  and  afterwards 
copper,  upon  highly  reflecting  polished  plates  of  brass  or  German 
silver,  which  have  been  first  provided  with  the  already  described 
detachable  intermediate  layer ;  the  metallic  precipitate  is  dried, 
and  then  detached  by  itself  or  after  being  glued  to  paper. 

Baths  Used. 

The  baths  used  for  precipitating  the  copper  have  the  usual  com- 
position : 

Water I  liter 

Crystallized  copper  sulphate 200  grams 

Concentrated  sulphuric  acid 30      " 

For  anodes  there  are  used  electrolytically  deposited  copper 
plates,  500x500  millimetres  and  8-10  millimetres  thick. 

The  precipitates  must  be  prefectly  smooth  and  free  from  pro- 
tuberances. To  this  end,  the  electrolyte  is  continuously  circulated 
and  while  circulating,  passed  through  a  filtration  apparatus  in  the 
form  of  a  small  filter  press  so  that  it  is  always  free  from  sus- 
pended solid  impurities.  The  single  baths  are  connected  in  series, 
the  cathode  plates  of  each  bath  in  parallel.  In  each  bath  there 
are  four  anodes  and  three  cathodes  and  between  them  moves  a 
mechanical  stirring  apparatus  provided  with  glass  rods.  The  ten- 
sion across  the  bath  is  only  one  volt  with  the  electrodes  about  10 
centimeters  apart,  and  a  current  density  of  about  10  amperes  per 
square  decimeter  is  used. 

The  dimensions  of  the  lead  lined  wooden  tanks  are  700  milli- 
meters long,  500  millimeters  wide  and  700  millimeters  deep.  If 
nickel  metallic  paper  is  to  be  produced,  a  plate  prepared  as  before, 
is  given  a  thin  film  of  nickel  precipitate  in  the  following  bath : 

Water I  litre 

Nickel  sulphate,  NiSO4 80  grams 

Ammonium  chloride,  NH4C1 20     " 

Boracic  Acid,  H3BOa 10      " 

The  nickel  deposit  requires  about  one  minute,  a  current  density 
of  about  0.5  ampere.  The  bath  tension  is  2.3  volts  with  the  elec- 
trodes 10  centimetres  apart.  The  tanks  for  the  nickel  baths  are  of 

3 


66  MANUFACTURE  OF  METALLIC  OBJECTS 

meters  deep,  and  have  supports  and  clamps  for  one  cathode  and 
two  anodes.  The  anodes  are  of  rolled  and  of  cast  nickel  sheets 
mixed  in  equal  numbers. 

Operation. 

The  German  silver  plates,  400x500  millimeters  are  maintained 
with  a  highly  lustrous  polish  in  order  that  the  metallic  leaves  may 
have  a  similar  lustre  and  may  be  most  easily  detached.  In  the 
plant  in  question  there  are  used  for  this  process  three  polishing 
motors  of  2^/2  H.P.  each,  driven  by  a  single  generator.  For  pol- 
ishing there  is  used  a  composition  of  grease  and  lime.  After  pol- 
ishing, the  plates  are  freed  from  grease  by  lime  water  and  pass 
then  to  the  oxidizing  or  sulphiding  baths.  The  time  of  this  opera 
tion  is  about  5  minutes.  After  careful  washing  with  water  they 
are  placed  in  the  baths.  They  remain  about  30  minutes  in  the 
copper  baths,  which  are  arranged  in  series  of  30,  there  being  two 
such  series.  Each  series  is  run  by  a  motor-generator  furnishing 
125  amperes  at  35  volts.  The  operation  is  uninterrupted  since  for 
every  plate  taken  out  of  the  bath  a  new  one  is  immediately  in- 
serted in  order  to  avoid  irregularity  in  the  current-density  rela- 
tions. The  coppered  plates  are  given  another  washing  and  then 
placed  in  a  drying  room  to  remove  the  last  traces  of  moisture, 
and  then  passed  to  pressing  rolls  where  the  paste  is  fed  to  them 
from  a  holder,  the  pasted  surface  covered  with  paper  and  then  the 
plate  and  paper  pass  together  through  two  pressure  rolls.  The 
pasted  plate  is  again  dried  and  the  metallic  paper  then  detached 
by  loosening  the  edges  with  a  knife-like  instrument. 

Gaskets. 

If  copper  foil  is  to  be  made  which  is  not  to  be  pasted  on  paper, 
the  copper  precipitate  is  made  somewhat  heavier,  the  time  of  depo- 
sition being  lengthened  to  45  minutes,  using  the  same  current 
density  as  before.  The  flanged  gaskets,  that  is,  metallic  copper 
gaskets  with  asbestos  filling,  are  manufactured  on  a  large  scale 
in  the  works  in  question  and  have  the  following  advantages.  They 
are  extraordinarily  soft  and  possess  in  consequence  of  their  tough 
elastic  copper  coating  an  extraordinary  capability  of  making  a 
tight  joint,  thus  utilizing  to  the  greatest  extent  the  yielding  qual- 


MANUFACTURE  OF   METALLIC  FOIL 


67 


ity  of  the  asbestos.  In  this  manner  the  asbestos  filling  is  protect- 
ed against  the  strong  decomposing  action  of  the  steam,  condenser 
or  cooling  water,  etc.,  being  protected  by  the  seamless  copper 
coating  closed  on  the  inside. 


'a, 


Fig- 


a  is  the  asbestos  filling,  b  the  copper  coating.  In  consequence 
of  the  continuous  metallic  surface  of  the  ring,  the  burning  fast 
of  the  gasket  surfaces  is  prevented  and  the  asbestos  filling  is 
therefore  capable  of  being  used  over  many  times.  The  gaskets 
are  manufactured  by  the  quick  electrolytic  plating  process  devis- 
ed by  the  author,  the  dynamo  furnishing  a  thousand  amperes  at  6 
volts,  and  driven  by  a  separate  electric  motor,  furnishing  current 
for  a  3,000  liter  bath.  The  electrolyte  is  kept  in  oscillation  by  a 
compressor;1  a  tank  has  9  cathodes  and  10  anodes  in  parallel.  The 
thickness  of  the  precipitate  is  controlled  by  ammeters  attached  to 
each  cathode  conductor  so  that  the  bath  is  run  independently  of 
the  size  of  the  various  electrodes.  The  thickness  of  the  copper  de- 
posit is  brought  to  o.i  or  0.2  of  a  millimeter,  the  duration  of  the 
process,  depending  upon  the  current  density  used,  is  15  hours  for 
a  current  density  of  6  amperes  per  square  decimeter  (see  the  cor- 
responding table). 

1  See  Pfanhauser  "  Elektroplatierung,  Galvanoplastik  und  Metalpolierung,"  4th  Ed., 
1900. 


68  MANUFACTURE  OF  METALLIC  OBJECTS 

Brass  rings  are  used  as  cathodes  which  are  nickeled  and  pro- 
vided with  an  intermediate  stratum  similar  to  that  used  in  the 
plates  for  the  manufacture  of  the  metallic  paper.  The  rings  are  as 
thick  as  the  asbestos  filling  for  which  the  copper  coating  is  to  be 
made ;  mostly  5  millimeters.  The  copper  precipitates  are  loosened 
with  a  spatula-like  instrument,  the  skill  of  the  workman  being  an 
important  factor  in  this  work. 

Power  Plant. 

As  a  source  of  power  there  is  a  50  HP.  steam  engine  furnishing 
regularly  35  HP.,  a  dynamo  attached  to  the  machine  gives  current 
for  the  whole  of  the  electrical  power  required.  The  plant  has  a 
total  floor  surface  of  some  600  square  meters  (6,600  square  feet), 
and  produces  daily  3,000  sheets  of  metallic  paper  and  2,000  gasket 
rings  and  employs  normally  60  hands.  The  copper  used  per  year 
amounts  to  about  30  tons.  The  capital  of  the  firm  is  $70,000. 

Costs  and  Profits. 

The  firm  of  Landauer  &  Company  have  most  kindly  communi- 
cated to  me  their  balance  sheets  of  costs  and  profits,  which  I  am 
permitted  by  them  to  reproduce  here. 

DAII.Y  OPERATING  EXPENSES. 

300  H.P. -hours  at  i^c I    3  75 

100  kilograms  of  electrolytic  copper 30  oo 

60  workmen  at  loc.  per  hour 60  oo 

Superintendent  at  $1,000  per  year 3  37 

10%  sinking  fund  on  capital 23  75 

5  %  interest  on  the  capital 1187 

40%  Government  tax  on  wages 24  oo 

Unforseen 5  75 

Total $162  50 

DAILY  OUTPUT. 

3,000  sheets  of  metallic  paper  at  $90  per  i  ,000 $270  oo 

2,000  Gaskets  at  $300  per  1,000 600  oo 


$870  oo 

30  %  discount  for  the  trade $261  oo 

Producing  cost 16250 

1423  50 

Daily  profits $446  50 

The  process  of  Landauer  is  carried  on  in  Vienna  by  the  Gal- 
vanic Metal  Paper  Works,  formerly  Landauer  &  Company;  this 
firm  also  grants  licenses  for  production  in  all  other  countries. 


MANUFACTURE  OF  METALLIC  FOIL 


LEAF  SILVER  AND  LEAF  GOLD. 

The  manufacture  of  leaf  silver  and  leaf  gold  is  quite  easily 
accomplished  by  the  principle  of  removable  electrolytic  coatings. 
From  the  many  patents  on  this  subject  I  select  for  mention  those 
of  Wood,1  Perner,2  and  Brandt  &  Nawrocki.3 . 

PROCESS  OF  BRANDT  &  NAWROCKI. 

This  process  uses  copper  plates  as  cathodes,  and  for  avoiding 
the  adherence  of  the  precipitate  there  is  used  a  thin  intermediate 
layer  of  wax  applied  as  a  solution  of  wax  in  alcohol. 

Where  neutral  or  potassium  cyanide  solutions  are  customary  as 
for  gold,  silver,  nickel,  brass,  etc.,  a  solution  of  rosin  in  benzole 
has  been  proposed.  But  for  copper  which  is  separated  out  of  a 
strongly  sulphuric  acid  solution,  a  coating  of  wax  dissolved  in 
alcohol  of  a  strength  of  I  in  50  is  applied.  The  baths  used  are 
the  usual  galvanoplastic  baths  the  composition  of  which  can  be 
found  in  special  works  on  electro-plating. 
Time  of  Deposition. 

The  time  for  depositing  leaf  gold  and  leaf  silver  is  given  in  the 
following  table : 


Current  density  in  amperes  per  square  decimeter. 

Metal. 

Thickness 
of  the 
metal  leaves 

0.05 

O.I 

O.2 

0.3 

mm. 

Time  in  hours  and  minutes. 

r 

O.OOO2 

o6/2 

03^ 

01/2 

01 

1 

0.0005 

16 

08 

04 

02^ 

Silver   -{ 

0.00  10 
O.OO2O 

32 
1-04 

32 

08 
16 

05 

10 

.    1 
i 

0.0050 

2-36 

1-18 

39 

26 

L 

O.OIOO 

5-12 

2-36 

1-18 

52 

f 

O.OOO2 

^3 

o6/2 

03^ 

02 

I 

1 

0.0005 

32 

16 

08 

05  l/i 

Gold     •{ 

o.ooro 

O.OO2O 

1-04 
2-39 

32 
1-04 

16 

32 

10/2 
21 

1 
i 

L 

0.0050 

O.OIOO 

5-18 
10-36 

2-39 

1-20 

2-39 

1-46 

1  English  Patent  3,537,  Oct.  30,  1873. 
-  English  Patent  10,126,  Aug.  7,  1886. 
8  German  Patent  43,351,  Sept.  25,  1887. 


7O  MANUFACTURE  OF  METALLIC  OBJECTS 

In  the  manufacture  of  metallic  paper  from  gold  and  silver,  the 
deposit  of  noble  metal  is  usually  strengthened  by  a  galvanic  de- 
posit of  baser  metal  in  order  to  give  a  more  durable  and  a  more 
intimate  connection  of  the  metallic  leaf  with  the  paper.  Copper 
or  brass  is  mostly  used  in  the  case  of  gold  leaf  because  according 
to  experience  the  back  ground  works  through  the  thin  sheet  of 
gold  so  that  for  instance  copper  gives  to  the  sheet  gold  a  reddish 
tint,  to  silver  a  greenish  tint. 

Patent  Claims. 

1.  The  process  of  manufacturing  metallic  paper  (papier-mache 
or  the  like)  consisting  in  first  precipitating  upon  a  suitable  metal- 
lic plate  an  extremely  thin  metallic  coating  either  chemically  or 
galvanically,  drying  the  same,  furnishing  the  free  surface  of  the 
same  with  a  binding  material,  laying  upon  this  moistened  paper 
or  paper  pulp,  and  by  a  rolling  process  or  pressure  combining 
these  so  intimately  that  the  sheet  metal  together  with  the  paper 
can  be  detached  from  the  support  without  being  torn. 

2.  In  the  process  of  Claim  i,  the  variations:    (a)  that  in  place 
of  a  metallic  skin  two  or  more  metallic  films  of  different  metals 
superimposed  upon  each  other  are  produced  upon  the  backing 
plate  before  the  uniting  of  the  metallic  film  or  films  with  paper, 
paper  pulp,  papier-mache  or  the  like:    (b).     Instead  of  placing 
the  binding  material  first  upon  the  metal-skin  and  then  laying 
paper  upon  it,  the  placing  of  the  paper,  paper  pulp,  or  papier- 
mache,  or  the  like,  already  provided  with  a  binding  material  upon 
the  dry  metallic  film. 

PROCESS  OF  ENDRUWEIT. 

The  above  process  has  several  short-comings  such  as  the  small 
durability  of  the  leaf  metal  upon  the  paper,  and  the  necessity  of 
polishing  each  time  the  cathode  plates,  such  that  the  price  of  the 
metallic  paper  thus  produced  is  about  25  cents  per  pack.  C.  En- 
druweit1  claims  to  have  invented  a  method  by  which  the  same 
amount  of  metallic  paper  can  be  made  at  a  cost  of  2l/2  cents. 

Patent  Claims. 
i.  The  manner  of  conducting  the  process  of  Patent  43,351, 

1  German  Patent  68,561,  June  16,  1891  ;  American  Patent  510,013. 


MANUFACTURE  OF  METALLIC  FOIL  71 

Claim  i,  in  which  the  insulating  of  the  cathode  plate  from  the 
metallic  layer  is  done  by  means  of  a  sulphide  layer,  consisting  in 
moistening  the  plate  with  a  I  per  cent,  solution  of  alkaline  poly- 
sulphides  or  acid  hydrogen  sulphide  in  methyl  alcohol. 

2.  For  the  facilitating  of  the  union  of  the  metallic  precipitate 
produced  upon  the  cathode  plate  by  Claim  i,  with  sheet  paper  the 
process  of  placing  the  cathode  plate  provided  with  a  copper  or 
nickel  precipitate  for  a  short  time  in  a  solution  of  zinc  sulphate, 
being  at  the  same  time  made  the  cathode  of  an  electric  current, 
and  treating  the  precipitate  thus  produced  with  a  solution  of  am- 
monium sulph-hydrate,  mercaptan  or  allyl  sulphide  or  of  mixing 
of  the  just-named  materials  with  the  paste  used. 

Gilding  or  silvering  is  produced  by  rubbing  the  copper  pre- 
cipitate with  a  suitable  cyanide  solution  containing  gold  or  silver. 

PROCESS  OF  SCHROEDER. 

E.  Schroder1  patents  in  Germany  a  process  for  the  production 
of  cathodes  for  the  direct  producing  of  polished  metallic  leaves 
electrolytically. 

Schroder  covers  a  highly  polished  and  burnished  metallic  plate 
with  a  preliminary  layer,  a  sort  of  enamel  like  material,  which  on 
being  melted  upon  it  produces  a  thin  fluid  glaze  consisting  of 
metallic  oxides  or  similar  mixtures.  The  lustrous  polish  of  the 
backing  metal  sheets  passes  through  this  smooth  coating,  and  the 
metallic  precipitates  upon  these  glazes  are  quite  as  dense  and  lus- 
trous as  if  they  had  been  produced  upon  the  polished  metallic  plate 
itself.  A  single  enameling  suffices  for  several  precipitations  since 
the  metallic  sheets  are  very  easily  loosened  and  the  plate  is  at  once 
ready  for  a  new  coating. 

In  this  way  sheets  of  gold,  silver  and  nickel  are  easily  produced. 

Schroder  says  that  the  enameling  is  injured  neither  in  acid  or 
alkaline,  hot  or  cold  solutions ;  but  he  assumes  that  the  plates  are 
always  cathodically  polarized,  and  that  the  conducting  of  the  cur- 
rent is  as  explained  by  Streintz,2  according  to  which  the  metallic 
oxides  of  the  enamel  being  very  finely  subdivided  as  they  are  in 
such  glazes,  conduct  the  current  to  the  metallic  background. 

1  German  Patent  123,658,  April  6,  1900. 

2  Zeitschr.  f.  Elektrochemie,  7,  921. 


72  MANUFACTURE  OF  METALLIC  OBJECTS 

SHEET  GOLD  BY  SWAN'S  PROCESS. 

J.  W.  Swan1  produced  sheet  gold  electrolytically  upon  polished 
thin  copper  plates  using  any  usual  gold  plating  bath ;  the  metal 
being  made  as  thick  as  is  desired.  The  thin  copper  plates  are 
then  dissolved  in  ferric  chloride  solution  or  in  nitric  acid,  leaving 
the  gold  as  thin  perfectly  coherent  films.  In  this  way  leaves 
have  been  made  of  less  than  o.oooi  millimeter  in  thickness,  trans- 
lucent to  light. 

PRODUCTION  OF  PLANE  SURFACES— RIEDERS'  PROCESS. 

Rieders2  invented  a  process  for  the  manufacture  of  smooth 
surfaces  upon  cast  or  rolled  plates,  galvanoplastically.  The  ob- 
ject of  the  process  is  to  produce  highly  polished  surfaces  upon  un- 
even surfaces  such  as  are  necessarily  those  of  cast  plates,  and  to 


Fig.  14. 

thus  produce  flat  plates  of  a  determined  thickness.  This  process 
is  intended  to  displace  grinding  or  polishing  work  and  to  avoid 
the  loss  of  metal  connected  with  such  processes.  Rieders  uses  in 
his  really  ingenious  process  the  following  apparatus: 

Apparatus. 

A  polished  glass  plate  G  (Fig.  15)  is  fastened  in  the  electrolyz- 
irig  tank  and  polishes  the  metallic  plate  M  to  be  smoothed.  The 
spindle  bent  at  K  moves  loosely  in  a  bearing  A  of  the  metal  plate. 
The  plate  is  pressed  against  the  glass  table  G  by  the  movable 
heavy  roller  B,  while  the  motion  of  the  spindle  causes  the  plate  to 

1  1,'Electricien  XII.  (1896).  173. 

2  German  Patent  117,097,  Dec.  15,  1899. 


MANUFACTURE:  OF  METALLIC  FOIL 


73 


move  eccentrically.     The  anode  a  is  at  the  bottom  of  the  vessel 
parallel  to  the  plate  M. 


Other  Forms  of  the  Apparatus. 
The  appartus  can  also  be  constructed  as  shown  in  Fig.  16. 


In 


Fig.  16. 

this  the  plate  to  be  smoothed  is  moved  backwards  and  forwards 
by  an  eccentric  motion  while  the  weighted  roll  B  produces  the  de- 
sired pressure  upon  the  glass  plate  G. 

Manner  of  Working. 

If  a  metallic  plate  which  has  cavities  is  coated  in  the  ordinary 
way  with  a  metallic  precipitate,  either  the  precipitate  will  deposit 
evenly  and  leave  the  cavities  as  they  were,  or  by  fast  working 
the  precipitate  deposits  preferably  upon  the  projecting  points  ac- 
centuating the  unevennesses.  Rieders  is  of  the  opinion  that  the 
metallic  precipitate  forms  more  slowly  on  the  projecting  points 


74 


MANUFACTURE  OF  METALLIC  OBJECTS 


which  come  in  contact  with  the  glass  plate  since  they  are  continu- 
ously ground  off. 

The  action  of  the  glass  plate  appears  to  the  author,  however, 
to  be  not  completely  understood.1  But  it  must  be  assumed  as  a  fact 


Fig.  17. 

that  perfectly  even  plates  are  produced  by  the  apparatus,  such  as 

1  See  also  Zeitschr.  f.  Elektrochemie,  8,  88. 


MANUFACTURE  OF  METALLIC  FOIL  75 

are  used  as  plates  in  typographical  work.  There  is  a  certain  simi- 
larity between  this  process  and  that  of  Dumoulin,  which  will  be 
described  further  on,  yet  Rieders  says  nothing  of  using  a  greasing 
or  insulating  material  to  protect  the  projecting  parts  of  the  plate. 

ELMORE'S  PROCESS. 

F.  E.  Elmore1  has  worked  out  mechanically  a  process  for  the 
production  of  sheets.  He  makes  especially  with  his  apparatus 
electrolytic  metal  sheets  which  are  soft  and  which  can  be  pressed 
to  a  high  polish ;  such  as  for  instance,  copper,  tin,  silver,  and  the 
like.  . 

Apparatus. 

The  apparatus  is  shown  in  plan  and  elevation  in  Fig.  17.  The 
plate  a  is  moved  by  the  rollers  b±  from  left  to  right  in  the  direction 
of  the  arrows,  while  the  precipitate  in  smoothed  by  polishers.  The 
apparatus  is  driven  by  the  pulley  q,  the  rollers  by  the  worm  gear- 
ing. The  polishers  are  of  agate  or  of  the  like  and  rest  upon  the 
cross  rods  m,  which  are  rotated  by  the  main  shaft  i  by  an  eccen- 
tric. The  anodes  u  lie  above  and  below  the  plate  operated  upon. 
The  prepared  plates  are  taken  from  the  movable  table  a,  polished 
on  both  sides. 

Continuous  sheets  and  leaves  can  be  made  by  modifying  the 
apparatus  so  that  an  endless  metallic  ribbon  is  led  over  rollers,  a 
suitable  intermediate  layer  being  first  deposited  upon  it  in  any 
known  manner. 

1  English  Patent  9,214.  July  15,  1886. 


X.    PRODUCTION  OF  WIRE,  ETC. 


Advantages  of  Electrolytic  Copper  Conductors. 

It  has  so  far  been  practicable  to  produce  wire  of  electrolytic 
copper  only  in  such  condition  as  to  require  a  subsequent  drawing, 
at  least  always  when  it  is  to  be  sold  as  commercial  wire.  Excep- 
tions to  this  statement  may  be  the  quite  thin  leaves  which  are  used 
as  resistance  ribbons.  The  high  tensile  strength  possessed  by 
electrolytically  precipitated  copper  (see  the  work  and  investiga- 
tions of  Hubl)  are  possessed  by  no  other  electrolytic  deposited 
metal,  at  the  most  excepting  nickel,  concerning  \vhich  according 
to  my  knowledge  nothing  has  been  published  as  yet. 

It  is  known  that  the  conductivity  of  copper  is  extraordinarily 
influenced  by  impurities  and  it  is  the  chemical  purity  of  the  copper 
produced  by  pure  copper  sulphate  solutions  which  was  primarily 
so  greatly  prized.  In  1870  J.  B.  Elkington1  patented  a  process  by 
which  electrolytically  pure  copper  could  be  worked  into  wire  with- 
out being  melted. 

PROCESS  OF  ELKINGTON. 

The  method  consisted  in  first  precipitating  thin  copper  plates 
electrolytically  which  were  then  cut  into  square  strips.  These 
wrere  drawn  out  as  usual,  and  when  round  in  shape  thickened  up 
in  the  copper  bath  and  again  drawn. 

FOX'S  PROCESS. 

E.  Fox2  improved  on  the  above  patent  in  relation  to  the  copper- 
ing of  the  wires,  devising  a  suitable  apparatus  which  had,  how- 
ever, no  particular  novelties. 

ACHESON'S  PROCESS. 

E.  G.  Acheson3  patented  a  method  of  producing  conducting 
wires  which  contain  two  separate  insulated  conductors.  The 
metallic  core  of  this  double  conductor  is  provided  with  a  coating 

1  English  Patent  2,525.  Sept.  20,  1870. 

2  English  Patent  3.455,  Aug.  27,  1879. 

3  German  Patent  38,914,  June  2,  1886;  English  Patent  7,394,  June  2,  1886. 


PRODUCTION  OF  WIRE,  ETC  77 

of  asphalt  or  the  like  and  by  drawing  through  a  box  holding 
graphite,  is  brushed  over  by  mechanical  means  with  a  layer  and 
made  conducting.  The  wire  is  then  coated  electrolytically  with  a 
layer  of  copper,  using  at  first  a  high  current  density  and  later  a 
lower  one  until  the  desired  thickness  is  obtained.  The  high  cur- 
rent density  must  be  used  at  first  in  order  to  copper  over  the 
graphite  quickly  while  the  subsequent  smaller  current  density  has 
the  purpose  of  making  the  precipitate  pliable.  The  bath  tension 
is  three  volts  at  the  beginning,  and  after  the  graphite  has  been 
coppered  over  this  is  reduced  to  one  volt. 

Patent  Claims. 

1.  An  electrolytic  conductor  consisting  of  a  wire  and  insulating 
envelope  of  fibrous  material  and  asphalt,  a  thin  layer  of  electroly- 
tically precipitated  copper,  a  further  coating  of  a  metallic  alloy 
and  a  protecting  envelope. 

2.  The  process  of  manufacturing  the  conductor  described  in 
Claim  i,  consisting  in  coating  over  a  layer  of  fibrous  material  and 
asphalt  by  brushing  with  graphite  and  so  making  it  conducting, 
and  passing  it  continuously  first  through  a  small  bath  using  a  high 
electromotive   force  wherein  is   deposited   a  proportionate   hard 
crystalline  layer  of  copper,  and  subsequently  in  a  larger  bath 
where,  by  a  feebler  current,  a  softer  and  more  flexible  copper  pre- 
cipitate is  produced ;  and  passing  the  wire  then  through  a  bath  of 
an  easily  fusible  metallic  alloy. 

TAVERNIER'S  PROCESS. 

E.  A.  Tavernier1  proposed  to  strengthen  thin  copper  wires 
manufactured  in  the  ordinary  way  by  passing  them  through  a 
trough  by  means  of  several  rollers  so  that  the  path  of  the  wire 
through  the  bath  is  as  great  as  possible. 

The  construction  of  the  apparatus  is  very  simple.  The  wire 
runs  inside  the  bath  on  insulated  rollers  either  of  porcelain  or 
glass  and  outside  the  bath  upon  metallic  rollers  which  drive  the 
apparatus.  Between  the  wires  are  the  anodes,  and  the  electrolyte 
is  continuously  moved  by  means  of  a  suction  pump. 

1  English  Patent  1,680,  Jan.  29,  1891. 


7&  MANUFACTURE  OF  METALLIC  OBJECTS 

PROCESS  OF  SWAN. 

J.  W.  Swan1  uses  the  principle  of  precipitating  copper  continu- 
ously upon  a  cathode  and  then  drawing  it  continuously  through 
draw-plates  in  the  process  itself,  thereby  producing  a  smooth  sur- 
face and  the  desired  section. 

Patent  Claims. 

1,  The  process  of  manufacture  of  wire  by  electrolytic  precipi- 
tation and  drawing  wherein  the  wire  is  simultaneously  moved 
through  an  electrolytic  bath  and  backwards  and  forwards  through 
a  drawing-plate. 

2.  The  apparatus  for  the  carrying  out  of  the  process  of  Claim 
i  in  which  at  both  ends  of  the  trough  A  provided  with  draw- 
plates  FFa  are  placed  drawing  cones  DD±  and  drums  EE1?  upon 
which  the  wire  is  wound,  and  rotating  these  automatically  by  a 
source  of  power  so  that  the  wire  is  moved  alternately  backwards 
and  forwards  through  the  bath  and  the  drawingplates. 

Apparatus. 

Swan  uses  for  his  apparatus  that  shown  in  Fig.  18.  In  a  long 
narrow  trough  A  is  an  electrolyte  of  normal  composition.  The 
two  ends  of  the  trough  are  closed  by  the  plates  FFj  provided  with 
the  drawing  holes.  Outside  of  the  plates  FF±  are  spaces  CQ,  in 
which  are  two  drawing  drums  DDj  which  keep  the  wire  stretched. 
From  here  the  wire  passes  upon  a  much  larger  drum  EEt  in  a 
washing  box  where  the  wires  are  washed.  The  driving  of  the 
drum  EEj  is  by  means  of  the  pulley  JJX.  The  wires  are  connected 
as  cathodes  with  a  source  of  current  by  the  contacts  M  and  the 
current  is  lead  in  by  the  brushes  N.  The  conductors  N  are  passed 
through  glass  tubes  and  insulated  from  the  copper  anodes  ii  by 
bushings  of  non-conducting  material.  There  are  several  such 
conductors  in  a  bath. 

Placing  of  the  Wires  in  the  Apparatus. 

The  wires  are  so  placed -in  the  apparatus  that  at  one  end  of  the 
trough  A,  for  instance,  the  end  adjacent  the  drum  D±,  the  wire  is 
passed  through  the  hole  in  the  draw-plate  F±  and  then  fastened 

1  German  Patent  63,030,  Oct.  9,  1891 ;  English  Patent  19,586,  Dec.  i,  1890 ;  see  also  lyum. 
elektr.  E.  Andreoli,  (1892),  45,  66. 


8o  MANUFACTURE:  OF  METALLIC  OBJECTS 

upon  the  drum  D^  The  latter  is  then  turned  until  a  length  of 
wire  equal  to  the  length  of  the  trough  is  wound  up.  The  fastened 
end  is  then  loosened  and  the  drum  again  revolved,  the  loose  end 
then  being  fastened  to  the  drum  Et.  This  is  continued  until  the 
wire  is  completely  drawn  through  and  wound  up  upon  the  drum 
whereupon  the  other  end  is  passed  through  the  drawing  plate  F 
at  the  other  end  of  the  trough  and  fastened  to  the  drum  D.  Each 
of  these  wires  which  serves  as  a  carrier  for  the  precipitate  should 
be  at  least  four  times  the  length  of  the  trough  A. 

Operation. 

For  making  copper  or  silver  wires  the  bath  is  worked  at  a  tem- 
perature of  20°  C.  The  apparatus  serves  also  for  the  manufacture 
of  nickel  wires,  but  must  be  altered  to  work  with  warmer  solu- 
tions. For  copper  a  tension  of  i  volt  is  used  and  the  bath  con- 
tains not  more  than  3  per  cent,  of  free  sulphuric  acid,  otherwise 
the  copper  suffers  in  regard  to  tensile  strength.  The  table  in  the 
appendix  gives  exact  figures  concerning  the  current  strength 
used.  It  is  self-evident  that  the  current  strength  to  be  used  is 
regulated  according  to  the  number  of  meter  lengths  of  wire  being 
electrolytically  produced  as  well  as  according  to  the  diameter  of 
the  same  which  regulates  the  surface. 

The  rate  of  drawing  is  regulated  according  to  the  current  den- 
sity used  and  the  dimensions  of  the  drawing  holes.  With  a  nor- 
mal current  density  of  I  to  i]/2  amperes  per  square  decimeter  the 
velocity  of  drawing  \vould  not  be  more  than  I  meter  per  minute, 
in  order  to  bring  the  surface  of  the  wire  as  often  as  possible  in 
contact  with  the  edges  of  the  drawing  holes  and  so  to  produce  a 
compression  and  smoothing  of  the  deposited  copper. 

Two  electric  motors  ee^  are  best  adapted  for  driving  the 
apparatus,  each  furnishing  i  horse-power.  These  two  motors 
rotate  the  drums  DDj  alternately  so  that  the  wire,  becoming  al- 
ways thicker  as  the  deposit  increases,  is  drawn  forwards  and 
backwards  through  the  holes  of  the  draw-plate  FFX  and  wound 
up  on  the  drums  EE^  While  the  wire  is  drawn  by  the  drums  D 
or  D!  from  the  trough,  fresh  wire  is  simultaneously  wound  off  the 
other  drum  Dx  or  D  and  is  carried  forward  into  the  trough  by  the 
winding  drums  and  there  receives  a  fresh  coating.  When  this 


PRODUCTION  OF  WIRE,  ETC 


8l 


newly  coated  and  thickened  wire  comes  to  the  other  end  of  the 
trough  it  is  drawn  through  the  draw-plate  there  and  wound  up 
-at  that  end ;  then  the  direction  is  changed  and  the  operation  is  so 
conducted  until,  because  of  the  deposit  of  metal  from  the  bath, 
the  desired  length  of  wire  has  been  produced. 

The  two  driving  drums  D  and  Dx  could  be  automatically  oper- 
.ated  by  an  arrangement  to  be  described  later,  or  in  case  electric 
motors  are  used  for  driving,  a  suitably  connected  switch  could 
be  operated  by  a  contact,  best  placed  on  the  end  of  the  ware  so  as 
to  throw  the  electric  motors  e  and^  alternately  into  and  out  of 
.action.  It  may  be  seen  in  Figs.  18  and  19  that  each  of  the  two 


Fig.  19. 

•drums  D  and  Dt  is  driven  by  its  own  electric  motor  by  the  pulleys 
/  g  and  worm  gear  drive  k  I.  If  it  is  desired  the  source  of  power 
can  be  directly  connected  with  the  screw  shaft  h  by  a  coupling. 
A  pawl  m  fastened  to  the  gear  wheel  is  held  against  the  ratchet 
wheel  o  fastened  upon  the  axle  of  the  drum  D,  by  the  pressure 
of  a  spring  n.  The  spur  wheel  q  fastened  to  the  gear  wheel  /  on 
•one  of  its  spokes  is  turned  around  one  tooth  at  each  revolution  of 


82 


MANUFACTURE  OF  METALLIC  OBJECTS 


the  gear  wheel  /  by  striking  against  a  fixed  projection  of  the  latch 
r.  The  latter  prevents  a  reversal  of  the  wheel  q.  At  each  revo- 
lution the  wheel  q  lifts  by  a  small  rod  the  latch  m  out  of  the 
toothed  wheel  o,  so  that  the  drum  can  turn  freely  in  the  reversed 
direction  by  a  pull  of  the  wire  from  the  drum  at  the  other  end 
of  the  trough. 

Simultaneously  with  the  lift  of  the  latch  or  immediately  there- 
after the  current-making  contact  m  fastened  on  the  wheel  q 
touches  another  contact  and  makes  electrical  connection  between 
this  and  a  current  closing  piece  upon  the  wheel  I,  whereby  the  cir- 
cuit is  closed  by  the  switch  throwing  the  formerly  operating 
motor  out  of  the  circuit  and  the  other  electric  motor  into  the  cir- 
cuit so  that  the  direction  of  motion  of  the  wire  is  reversed.  In 
this  way  the  wire  is  mechanically  drawn  backwards  and  forwards 
until  the  desired  length  has  been  produced  and  the  wire  is  of  the 
desired  thickness. 

According  to  the  calculations  of  the  author  a  trough  10  meters 
long  should  produce  in  10  hours  the  following  quantities,  if  it  is 
assumed  that  30  draw-holes  are  used  so  that  there  is  exposed  to 
the  electrolytic  deposition  300  meters  of  wire  at  one  time. 


Diameter 
of 
wire  in 
mm. 

Weight  pro- 
duced in 
10  hours 
Kg, 

Current  'used 
for  whole 
apparatus  in 
amperes.1 

Surface  per 
running  meter 
in  square 
decimeters. 

Area  of 
wire 
in  square 
millimeters. 

Weight 
per  meter 
in 
grams. 

I 

14.2 

1  2O 

0.31 

0.79 

6.99 

2 

28.4 

240 

O.62 

3-H 

27.96 

3 

42.6 

360 

o-93 

7.07 

62.95 

4 

56.8 

480 

1.24 

12-57 

III  .90 

5 

70  o 

600 

1-55 

19.64 

174.80 

It  is  to  be  seen  from  this  compilation  that  the  smaller  wires  are 
made  under  unfavorable  conditions,  because  the  cost  of  operating, 
interest  and  sinking  fund  would  be  increased  when  making  them. 

Cost  of  Plant. 

For  a  wire-drawing  establishment  to  produce  100  kilograms  of 
copper  wire  daily  of  various  sizes  between  i  and  5  millimeters  in 
diameter  the  cost  of  plant  would  be  as  follows : 

1  Current  density  used  1.3  amperes  per  square  decimeter. 


PRODUCTION  OF  WIRE,  ETC  83 

3,500  square  yards  of  ground $  1,625.00 

Buildings  with  2,000  square  yards  of  shedding 875.00 

Boiler,  70  square  yards  of  heating  surface  with  mason- 
ry and  chimney 3,000.00 

60  H.P.  steam  engine,  including  foundation,  etc 2,500.00 

Main  generator,  35  Kw.,  with  switchboard 1,250.00 

35  Swan  apparatus,  including  electric  motors 12,500.00 

Switchboard,  measuring  instruments,  conductors,  etc  1,125.00 

Brection,  packing,  freight , 1,500.00 

Putting  in  operation 625 .00 

Total  cost  of  plant $25,000.00 

Operating  Costs. 
For  a  plant  of  the  above  capacity  the  operating  costs  would  be : 

Coal:  3.3  Ibs.  per  H.P. -hour,  per  year  of  300  days  of 

24  hours  each  —  650  tons  at  $3.75 $  2,437.50 

72  tons  of  blister  copper  at  $237.50 17,100.00 

Wages  of  the  foremen 1,500.00 

Wages  of  one  clerk 500.00 

Wages  of  one  engineer 375-Qo 

Wages  of  two  firemen 550.00 

Wages  of  ten  workmen 2,500.00 

Dynamo  brushes,  grease  and  polishing  material 750.00 

5  %  interest  on  capital 1,250.00 

iofc  sinking  fund 2, 500.00 

Light,  heating,  etc 250.00 

Total  yearly  operating  cost $29,712.50 

Profits. 

Assuming  the  price  of  copper  wire  at  41.50.  per  kilogram 
(18.640.  per  pound)  and  that  the  above  plant  produces  yearly 
72,000  kilograms  =  159,400  pounds,  the  profits  would  stand  as 
follows : 

72,000  kilograms  of  wire  at  42. 5c.  per  kilogram 

(i8.64C.  per  pound) $29,880.00 

Value  of  0.4%  silver  content  of  the  blister  copper  at 

$19.00  per  kilogram 5,500.00 

Value  of  0.003%  g°ld  content  at  $700  per  kilogram  . .     1,500.00 


Total $36,880.00 

Operating  cost 29,712.50 

Yearly  profits $  7,167.50 

Corresponding  to  a  dividend  of  28  per  cent. 


84  MANUFACTURE:  OF  METALLIC  OBJECTS 

Applications. 

The  fundamental  condition  for  the  profitability  of  this  attract- 
ive process  is  the  obtaining  of  rich  blister  copper  since  it  can  be 
easily  calculated  that  if  electrolytic  copper  were  used  which  is 
free  from  the  noble  metals,  the  process  would  no  longer  be  profita- 
ble. Whenever  the  price  of  pure  electrolytic  copper  would  be 
over  28.75^  per  kilogram  the  process  would  also  be  unprofitable. 
PROCESS  OF  SANDERS. 

R.  D.  Sanders1  obtained  a  patent  together  with  a  number  of 
supplementary  patents,  the  claims  of  which  are  as  follows : 

The  production  of  wire  or  ribbon  electrolytically  by  means  of  a 
conical,  prismatic  or  otherwise  shaped  cathode,  the  working  sur- 
face of  which  is  spirally  grooved  with  the  adjacent  grooves  in- 
sulated from  each  other. 

A  cathode  for  the  production  of  wire  or  the  like  electrolytically 
using  a  cathode  with  non-conducting  insulated  spaces,  similar  to 
that  of  patent  71,838,  characterized  by  so  forming  the  non-con- 
ducting spaces  or  the  conducting  cathode  spaces  that  the  desired 
sectional  shape  of  the  wire  or  ribbon  can  be  produced,  and  that 
the  metal  can  be  deposited  on  either,  sideways  or  in  a  direction 
perpendicular  to  the  cathode  surface. 

A  method  of  carrying  out  the  process  of  the  above  patent  for 
the  production  of  wire  and  like  objects,  characterized  by  placing 
in  the  grooves  of  the  mandril  used  as  cathode  a  wire  which  facili- 
tates the  detaching  of  the  electrolytic  deposit. 

The  production  of  wire  electrolytically  using  a  starting  wire  as 
a  depositing  surface,  which  wire  is  wound  upon  a  spindle  so  as  to 
be  detachable,  and  instead  of  being  sunk  into  deep  grooves  is 
wound  upon  the  surface  of  the  cylinder  or  in  such  shallow  de- 
pressions that  the  wire  projects  above  the  cylindrical  surface  of 
the  spindle  so  that  rubbing  contacts  would  lie  continuously  on  the 
starting  wire  or  on  the  deposited  metal. 

Principle  of  the  Process. 

From  these  patent  claims  it  can  be  seen  that  Sanders  works 

1  See  also  Zeitschrift  f.  Elektrochemie.  I,  428. 

German  Patent  71,838,  Feb.  16,  1892  ;  English  Patent  7,960,  May  8,  1891. 
German  Patent  73  824.  May  18,  1893  :  English  Patent  12.382.  July  4,  1892. 
German  Patent  78,361,  March  22,  1894;  English  Patent  13,93!.  July  *8,  1893. 
German  Pater.t  104,185,  Aug.  26,  1898. 


PRODUCTION  OF  WIRE,  ETC  85 

upon  the  principle  of  a  revolving  roller  using  a  conducting  roller 
wound  spirally  upon  a  mandril,  deposits  metal  electrolytically 
upon  it,  and  thus  produces  a  metallic  deposit  like  a  spiral  spring. 
Sanders  thereby  saves  much  space  and  simplifies  considerably  the 
apparatus  of  Swan.  The  wire  is  loosened  from  the  backing  and 
drawn  through  the  ordinary  apparatus  whereby  the  seams  of  the 
spiral  of  the  flattened  surfaces  which  are  against  the  mandril  are 
caused  to  disappear. 

First  Apparatus. 

Sanders'  first  apparatus  was  constructed  as  follows :  A  roller 
was  made  of  wooden  disks  clamped  together  and  placed  in  a 
holder  and  covered  over  with  a  non-conducting  or  a  conducting 
material.  In  this  coating  a  spiral  groove  was  cut  or  in  the  case 
of  the  non-conducting  coating  was  then  covered  with  a  conducting 
material  either  in  the  grooves  or  upon  the  ridges.  If  the  coating 
was  of  metal  the  grooves  were  filled  with  wax  or  a  similar  non- 
conducting material.  The  wax  having  hardened  the  whole  roller 
is  turned  so  that  the  ridges  of  the  metallic  surfaces  of  the  spiral 
grooving  are  visible.  If  a  conducting  material  is  to  be  used  the 
roller  with  its  coating  is  turned  smooth  and  is  given  a  metallic 
coating  such  a,s  tinfoil.  The  coating  having  become  hard  a  spiral 
groove  is  cut  in  which  leaves  upon  the  grooves  a  strip  of  the 
metallic  coating  in  the  form  of  a  spiral  line.  The  roller  is  as 
large  as  can  conveniently  be  used  which  allows  easier  winding 
off  of  the  finished  wire.  The  coating  is  best  made  of  asphalt  or 
the  like. 

Use  of  Finishing  Tools. 

While  the  roller  is  being  rotated  burnishing  tools  can  be  ap- 
plied to  it.  As  soon  as  the  tools  arrive  at  one  end  of  the  spiral  the 
direction  of  rotation  of  the -roller  is  reversed.  The  burnishing 
tools  are  carried  in  frames  which  move  in  guides  fastened  to  the 
sides  of  the  vessel.  The  motion  of  the  burnishing  tools  is  given 
by  the  spiral  winding  of  the  roller  itself. 

Second  Form  of  Apparatus. 

In  the  first  apparatus  the  metal  showed  a  tendency  to  grow 
upon  the  non-conducting  parts,  so  that  the  patent  73,824  was 


86 


MANUFACTURE  OF  METALLIC  OBJECTS 


directed  towards  the  use  of  angular  cathodes.     In  this  manner 
precipitates  of  nearly  circular  cross-section  are  obtained. 

Fig  20  shows  a  cathode  carrier  with  recessed  construction.   Be- 


Fig.  20.  Fig.  21. 

tween  the  strips  b  are  layers  c  of  non-conducting  material  in 
which  are  embedded  metallic  plates  a  upon  which  the  precipitate 
is  formed.  Fig.  21  shows  a  cathode  carrier  upon  which  the  metal 
can  be  deposited  spirally  in  great  lengths.  If  wished,  this  cathode 
carrier  can  also  be  made  of  a  cylindrical  form.  In  all  cases  the 
visible  surfaces  of  the  metal  strips  upon  which  the  deposit  takes 
place  are  not  so  wide  as  the  bottom  of  the  grooves,  so  that  the 
deposited  metal  can  spread  sideways  as  it  increases  in  amount 
until  the  desired  cross-section  or  the  desired  amount  has  been 
reached.  In  a  similar  manner  it  is  evident  that  a  large  variety  of 
cross-sectional  forms  can  be  produced,  as  for  instance,  in  Fig.  22, 
in  which  a  spiral  groove  is  formed  upon  a  cylindrical  metallic 

a/ 


Fig.  22. 

mandril  d.  This  groove  is  rilled  with  non-conducting  material, 
and  then  the  whole  cylinder  turned  down,  leaving  upon  the  outer 
surface  a  thin  visible  metallic  line  a.  The  metal  precipitated  upon 
the  latter  takes  then  an  almost  circular  form.  In  taking  off  the 
wire  it  is  self-evident  that  the  surface  under  the  deposit  will  ap- 
pear as  a  long  groove  which  can  be,  however,  pressed  together 
afterwards.  For  producing  longer  wires  the  cathode  surface  is 
constructed  in  the  manner  shown  in  Fig.  23.  The  metal  band  is 
rolled  up  spirally  and  the  intermediate  spaces  filled  with  non- 
conducting material.  The  flat  sides  are  turned  off  or  cut  down  to 


PRODUCTION  OF  WIRE,  ETC  87 

the  edges  of  the  metallic  band  so  as  to  leave  visible  on  each  side 
a  thin  screw-like  metallic  surface  a. 


Fig.  23. 


If  the  deposited  metal  is  to  be  rubbed  during  the  deposition  an 
arrangement,  as  shown  in  Fig.  24,  is  used  in  which  the  cathode 


Fig.  24. 


Fig.  25. 


carrier  /  is  pivoted  in  a  vessel  k  and  a  roller  or  a  rubbing  pad  / 
lies  loosely  upon  the  upper  surface  of  the  cathode.  This  roller 
must  have  sufficient  weight  to  smooth  out  the  deposited  metal  by 
its  motion. 

Loosening  of  the  Wire. 

The  separating  of  the  backing  wire  from  the  precipitate  is 
facilitated  by  laying  in  the  grooves  of  the  mandril  or  roller  a  fine 
wire  which  forms  the  true  depositing  surface.  During  the  elec- 
trolysis the  groove  is  filled  up  with  the  deposited  metal  and  at  the 
end  the  metallic  precipitate  can  be  rolled  off  with  or  without  the 
original  wire.  It  is  required  to  make  a  smaller  groove  in  which 
the  wire  is  laid  so  that  it  cannot  be  surrounded  by  the  precipitated 


88 


MANUFACTURE  OF  METALLIC  OBJECTS 


metal.     The  mandril  consists  of  any  suitable  material  such  as 
porcelain  or  glass. 

Upon  the  mandril  is  a  spiral  groove  b  in  which  the  fine  wire  c 


Fig.  26. 

is  laid.  The  ridges  or  wrires  e  form  a  conductor  between  the  fine 
wire  c  and  the  larger  coductor  d,  their  free  ends  rest  upon  the 
upper  surface  of  the  wire  c  and  the  other  end  fastened  into  holes 
in  the  conductor  d  which  latter  is  held  by  a  bracket  /  fastened  to 
the  holder  g.  If  the  deposited  metal  is  such  that  it  does  not  ad- 
here to  the  original  wire,  such  as  is  the  case  with  lead  it  can  be 
removed  without  disturbing  the  original  wires. 

d 


Fig.  27. 

In  those  cases  where  the  conductor  is  arranged  outside  of  the 
mandril  or  kernel  the  latter  is  hung  upon  a  rotating  shaft,  and  in 
order  to  avoid  deposition  of  metal  upon  the  rods  e  is  so  hung  that 
a  part  of  its  circumference  extends  above  the  level  of  the  fluid. 
This  manner  of  supporting  the  mandril  can  also  be  used  when  the  ' 
material  of  the  mandril  encloses  the  conductor.  The  rotating 


PRODUCTION  OF  WIRE,  ETC  89 

shaft  h  is  turned  in  any  suitable  manner  by  the  pulley  i,  (see  Fig. 
27),  and  preferably  above  the  level  of  the  liquid  in  the  trough  g. 
By  this  arrangement  when  the  shaft  h  is  rotated  the  mandril  a  is 
by  friction  slowly  rotated  in  the  fluid.  Metal  is  deposited  upon 
the  wires  c  and  the  pencils  e  carry  the  current. 

Operation. 

In  operation  several  shafts  are  run  by  a  common  shaft  the  ro- 
tating speed  being  best  about  i  meter  per  minute.  The  power  re- 
quired per  roller  varies  according  to  the  number  of  burnishing 
tools,  the  size  of  the  trommel  and  the  surface  velocity,  and  is  be- 
tween 0.2  and  0.5  HP.  The  power  necessary  for  electrolysis  is 
not  included  in  this.  The  bath  tension  varies  between  0.25  and 
0.7  volt.  In  order  to  obtain  as  great  a  tensile  strength  and  the  best 
conductivity  of  the  wire  it  is  recommended  to  use  pure  electrolytic 
copper  or  blister  copper  containing  at  least  98  per  cent,  copper. 
The  burnishing  tools  are  best  made  of  agate  of  proper  shape  to 
give  to  the  wire  the  desired  form  in  which  it  is  to  be  sold.  For 
round  wires  agate  tools  are  used,  which  are  cut  with  a  semi- 
circular groove  in  them. 

Cost  of  Plant. 

In  order  to  compare  this  process  with  that  of  Swan  the  cost 
of  the  plant  will  be  calculated  likewise  for  a  production  of  100 
kilograms  of  copper  wire  per  day ;  the  wire  being  assumed  as  5 
millimeters  in  diameter,  which  can  then  be  drawn  to  any  desired 


size. 


COST  OF  PLANT. 

Ground,  about  10,000  square  feet $  250.00 

Building  for  electrolytic  and  drawing  plant,  with 

office  and  dwelling  for  the  superintendent 2,500.00 

Boiler  of  300  square  feet  heating  surface,  including 

masonery  and  foundation 1,375.00 

Steam  engine,  30  H.P 1,750.00 

30  Sanders'  apparatus,  3  feet  long  and  2  feet  diameter 

including  burnishing  tools 6,375.00 

7,500  gallons  of  electrolyte 875.00 

10  Kw.  dynamo 625.00 

Switchboard  with  equipment  and  conductors 1,000.00 


9O  MANUFACTURE  OF  METALLIC  OBJECTS 

Drawing  apparatus  and  reels 1,200.00 

Belts  and  pulleys 1,125.00 

Washing  tanks 200.00 

Brection,  packing,  freight - 500.00 

Starting  expenses 925.00 

Total $18,750.00 

OPERATING  COST. 

The  following  values  can  be  assumed: 

Coal  3.3  pounds  per  H. P. -hour  at  $3.75  per  ton  =  per 

year $  1,250.00 

72  tons  of  98  per  cent,  blister  copper  at  1237.50  per  ton  17, 100.00 

Superintendent i  ,500.00 

Clerk 500.00 

One  engineer 375-°° 

Two  firemen 55°-°° 

Fifteen  workmen 3,750.00 

Dynamo  brushes,  lubricating  oil,  etc 75Q-°o 

Five  per  cent,  interest  on  capital 937-5° 

Ten  per  cent,  sinking  fund  on  the  capital 1,875.00 

Lighting,  heating,  etc 250.00 

Total,  about $28,837.50 

PROFITS. 

Assume  the  same  selling  price  of  the  wire,  that  is  41. 5c.  per 
kilogram  (i8.8/c.  per  pound). 

72  tons  of  wire $29,880.00 

Value  of  0.4  per  cent,  silver  in  blister  copper  at  $19.00 

per  kilogram 5,500.00 

Value  of  0.003  Per  cent,  gold  in  blister  copper  at 

$700  per  kilogram 1,500.00 

$36,880.00 
Operating  cost 28,837. 50 

Yearly  profits  about $  8,042.50 

Corresponding  to  a  yearly  dividend  of  almost  43  per  cent. 
It  is  therefore  seen  that  the  Sanders  process  possesses  a  better 
outlook  than  the  Swan,  starting  with  the  same  conditions.  I  must 
remark  that  the  price  of  the  Sanders  apparatus  has  been  found 
by  approximate  calculation,  and  there  may  be  some  further  varia- 
tion in  the  value  from  that  given. 


PRODUCTION  OF  WIRE,  ETC 


PROCESS  OF  FORSYTH  AND  FLETCHER. 

A  process  similar  in  principle  to  that  of  Sanders  for  producing 
metallic  ribbons  and  rods  was  patented  by  Forsyth  and  Fletcher. 
The  apparatus  used  by  them  is  constructed  as  follows  i1 

Apparatus. 

The  wrought  iron  cylinder  F  closed  at  both  ends  is  covered  at 
the  ends  with  an  insulating  layer  B,  on  the  sides  with  a  metallic 
covering  of  easily  worked  metal  G.  (Figs.  28-30).  A  spiral 


Fig.  28.  Fig.  29.  Fig.  30. 

groove  of  trapezoidal  cross-section  is  cut  in  the  metallic  sheath 
with  the  larger  base  of  the  trapezium  beneath  and  in  these  grooves 
strips  of  insulating  material  K  are  placed,  which  may  be  of  rub- 
ber. 

This  roller  is  then  hung  as  a  cathode  in  an  electrolytic  metallic 
vessel  and  rotated,  when  the  metal  deposits  between  the  rubber 
strips  K,  so  that  when  the  electrolysis  is  stopped  it  may  be  wound 
off  as  a  metallic  band,  or  if  the  electrolysis  is  carried  on  longer 
may  be  obtained  as  wire  or  rod  having  a  cross-section  determined 
by  the  form  of  the  rubber  strips  between  which  it  is  deposited. 

PROCESS  OF  COWPER-COLES. 

To  complete  the  list  of  these  processes  I  mention  that  of  Cow- 
per-Coles,  by  which  sheet  metal  or  metal  strips  or  wire  may  be 
produced  in  any  desired  lengths. 

Apparatus. 

Cowper-Coles2  deposits  the  metal  upon  an  endless  copper  band 
which  is  drawn  so  slowly  through  the  electrolyzing  vessel  that 

1  American  Patent  570,125,  Oct.  27,  1896  ;  see  also  Zeitschr.  f.  Elektrochemie,  3,  346. 

2  English  Patent  2,998,  1895  ;  Zeitschrift  f.  Elektrochemie,  2,  648. 


92 


MANUFACTURE  OF  MlyTALUC  OBJECTS 


the  precipitate  on  leaving  the  bath  is  of  the  desired  thickness ;  it 

Fig-  32. 


Fig-  3i- 


is  then  separated  from  the  band  outside  of  the  bath  and  rolled  up 
on  a  reel.     (See  Figs.  31  and  32). 


XL    MANUFACTURE  OF  BODIES  OF  LARGE 

SIZE. 


The  largest  application  of  electrolytic  metallic  depositing  pro- 
cesses is  the  manufacture  of  tubes  of  all  varieties ;  but  before 
turning  to  this  use  we  will  describe  those  processes  dealing  with 
the  manufacture  of  large  bodies  such  as  large  vessels,  parabolic 
mirrors,  etc. 

PROCESS  OF  J.  KLEIN. 

A  completely  new  method  of  producing  bodies  having  the  shape 
of  surfaces  of  revolution  of  most  varying  kinds  was  patented  by 
J.  Klein.1  This  investigator  likewise  compresses  the  metal  as  it 
is  being  deposited  by  causing  a  rotating  cathode  to  roll  against  a 
corresponding  shaped  straight  or  grooved  support. 

Patent  Claims. 

1.  The  process  for  the  compressing  and  forming  of  electrolytic 
precipitates  characterized  by  using  roller-like  cathodes  of  any  de- 
sired number  and  profile  and  rolling  them  upon  corresponding 
straight  or  grooved  supports  in  an  electrolyte  bath  until  the  end 
of  the  operation. 

2.  The  carrying  out  of  the  process  described  in  Claim  I  by  the 
use  of  an  apparatus  consisting  of  one  or  more  frames  in  which 
(according  to  the  number  of  the  bodies  to  be  produced  at  once) 

either  one,  two  or  more  rotating  mandrils  are  rolled  upon  a  verti- 
cal, inclined  or  horizontal  or  curved  support,  backwards  and  for- 
wards, until  the  precipitate  upon  the  mandril  is  of  the  desired 
thickness. 

3.  The  apparatus  of  the  kind  described  in  Claim  2  in  which 
the  mandril  is  hollow  and  open  at  one  or  both  ends  and  the  metal- 
lic deposit  upon  which  is  compressed  by  smoothing  irons  while 
the  deposit  upon  the  inner  surface  of  the  mandril  is  compressed 
by  one  or  more  rollers  carried  upon  a  rotating  frame. 

1  German  Patent  79,764,  March  31,  1892  ;  English  Patent  563,  Jan.  9,  1895  ;  see  also  Zeit- 
schrift  f.  Elektrochemie,  i,  161  ;  Dr.  G.  I^angbein. 


94 


MANUFACTURE  OF  METALLIC  OBJECTS 


4.  An  apparatus  of  the  kind  described  in  Claim  2  so  altered  that 
it  or  at  least  the  frame  is  arranged  as  a  turning  rack  within  whose 
sweep  the  mandrils  are  rotated  and  so  radially  movable,  while  the 
form  has  the  shape  of  a  fixed  hollow  cylinder  the  inner  or  outer 
circumference  of  which  is  rolled  by  the  movement  of  the  turning 
rack. 

5.  The  apparatus  of  the  kind  described  in  Claim  2  in  which  the 
frame  is  arranged  as  a  rotating  disc  which  in  its  motion  rolls  the 
mandrils,  arranged  radially  about  its  turning  axis,  upon  a  hori- 
zontal plate. 

As  far  as  concerns  the  process  used  by  Klein  it  can  be  judged 
from  the  same  how  the  process  is  carried  out  since  the  different 
constructions  of  the  mandrils  as  well  as  the  whole  apparatus  are 
minutely  described. 

Manufacture  of  the  Mandrils. 

The  mandrils  upon  which  the  metal  precipitate  is  deposited  con- 
sist either  of  metal  or  wood  and  can  be  hollow  or  solid.  See  fig- 
ures 33  to  36. 


f 

Fig.  33-  Fig-  34-  Fig.  35-  Fig.  36. 

Fig.  33  shows  a  solid  mandril,  Fig.  34  a  hollow  one,  Fig.  35,  one 
which  is  stiffened  by  an  included  tube,  while  in  Fig.  36  the  man- 
dril is  stiffened  inside  by  one  or  more  cross  ribs. 


Fig.  37- 

The  adjustment  of  such  hollow  mandrils  is  made  clear  in  Fig. 
37.  The  mandril  is  closed  by  the  plug  e,  which  has  a  small  screw 
plug  b  and  a  conducting  contact  e,  the  latter  having  the  form  of  a 
cap.  The  hollow  mandril  is  usually  filled  with  sand  or  lead  shot. 
The  stiffening  webs  of  the  mandril  are  then  filled  up  by  the  appli- 


MANUFACTURE  OF  BODIES  OE  LARGE  SIZE 


95 


cation  of  gypsum,  glue,  clay,  or  the  like,  or  at  once  coated  with  an 
easily  fusible  and  polishable  material,  such  as  wax,  lead,  paraffine, 
etc.  The  form  is  then  rolled  upon  the  properly  prepared  former 
giving  it  the  form  of  rotation  desired.  Instead  of  rolling  the  man- 
dril with  its  plastic  coating  it  may  also  be  turned'  down  to  the 
shape  desired;  the  surface  of  the  roller  is  then  made  conducting 
in  the  proper  way  if  it  is  of  non-conducting  material.  The  ar- 
rangement shown  in  Fig.  38  is  particularly  designed  for  produc- 


/  9 


Fig.  38. 

ing  hollow  rotated  bodies.  It  consists  of  two  exterior  parallel 
guides  a  screwed  down  to  a  base  k.  Between  these  guides  is  the 
form  c  having  the  profile  of  the  desired  article.  The  hollow  body 
is  carried  by  the  tube  d,  forming  the  center  of  the  mandril.  The 
ends  of  the  spindle  j  are  furnished  with  screws  in  order  to  hold 
the  article  fast  in  position.  On  both  sides  of  the  spindle  are  roll- 
ers g  and  guides  h  so  that  the  guides  a  lie  between  them.  The 
mandril  is  fastened  in  position  on  the  spindle  by  the  nuts  b. 

The  tube  d  is  then  coated  with  clay  and  rolled  backwards  and 
forwards  upon  the  base  c,  previously  rubbed  with  oil,  and  rolled 
until  the  desired  form  corresponding  to  the  base  has  been  ob- 
tained. The  guides  h  roll  freely  upon  the  track  a.  The  mandril 
is  now  burned  and  then  dipped  into  a  mixture  of  resins  or  wax, 
after  which  it  is  again  rolled  upon  the  former  in  which  operation 
the  rings  ii  placed  upon  the  sliding  guides  regulate  the  thickness 
of  the  coating.  In  putting  on  the  wax  coating  the  burned  form  is 
wetted  with  water  to  prevent  the  adhesion  of  the  wax.  The  man- 
dril so  coated  is  then  made  conducting  either  with  graphite  or 
with  an  easily  fusible  alloy  if  the  mandril  has  not  been  coated 
with  wax. 

For  the  forming,  various  arrangements  can  be  used  and  Figs. 
39  and  40  show  several  types.  This  forming  is  to  be  distinguished 


96 


MANUFACTURE  OF  METALLIC  OBJECTS 


from  the  forming  of  the  mass  of  clay  on  the  forming  table  since 
the  forming  arrangements  to  be  described  serve  to  compress  and 
polish  the  precipitate  during  the  electrolytic  process.  Figures  39 
and  40  show  quite  simple  apparatus. 

Simple  Form  of  Apparatus. 

In  the  electrolyzing  bath  A  the  forming  plate  h  is  placed  on  the 
supports  g,  being  of  hard  material  like  glass  or  procelain  not  at- 
tacked by  the  bath.  If  several  mandrils  are  to  be  simultaneously 
worked  they  can  if  they  have  the  same  profile  be  rolled  upon  the 


Fig.  39- 

same  forming  plate  if  they  are  put  together  in  the  frame  /,  being 
so  placed  in  the  frame  that  they  can  be  easily  taken  out  one  at  a 
time.  The  conducting  of  the  current  to  the  mandrils  is  by  the 
wire  w±  by  means  of  the  brush  L  fastened  to  the  frame  and  the 
already  mentioned  contact  pieces  on  the  ends  of  the  mandrils. 
The  anode  is  above  the  forming  mandrils  and  parallel  to  their 
direction  of  motion. 


Fig.  40. 


As  soon  as  the  current  is  put  on  metal  begins  to  deposit  on  the 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE 


97 


forming  shape,  and  the  frame  is  moved  backwards  and  forwards 
upon  the  forming  plate  by  an  eccentric.     Figs.  41  and  42  show  a 


Fig.  41. 


cross-section  of  the  forming  plate. 

Fig.  43  shows  a  form  of  apparatus  which  is  a  multiple  of  that 
shown  in  Figs.  39  and  40. 


Fig.  43- 

The  longitudinal  and  cross-sections  of  a  forming  vessel  are 
shown  in  Figs.  44  and  45.  In  this  several  forming  cylinders  can 
be  simultaneously  worked  over  in  a  vertical  direction  in  which 
case  the  frame  is  carried  by  the  rollers  r1  and  the  mandrils  are 
pressed  against  the  forming  plate  by  the  rollers  r2.  The  frames 
can  also  be  pressed  against  the  forming  plate  by  adjustable  wedges 
or  in  any  similar  manner.  The  anode  plates  are  bent  to  corre- 
spond approximately  with  the  profile  of  the  cylindrical  forms  and 
take  part  in  the  motion. 

Circular  Apparatus. 

Another  shape  of  the  apparatus  is  that  having  a  trough-shaped 
arrangement  of  the  forming  plate.  The  best  form  is  that  of  a 

4 


98 


MANUFACTURE  OF  METALLIC  OBJECTS 


hollow  cylindrical  arrangement  of  the  plates  because  in  that  case 
both  the  forming  plate  and  the  anode  can  be  given  the  desired 
profile  by  a  turning  operation.  Such  a  form  of  apparatus  is 


Fig.  44.  Fig.  45. 

shown  in  Fig.  46,  in  which  b  is  the  forming  plate  in  the  shape  of  a 
cylinder  and  fastened  to  the  outer  case  of  a  holder  c;  d  is  the  turn- 


Fig.  46. 


ing   frame   carrying  the   cylindrical   anode   /  and   two   discs    e 
on  the  axle  of  the   forming  cylinder   lie   in   slits   opening  out- 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE 


99 


wardly.  If  the  turning  frame  d  is  moved  alternately  in  one  or  the 
other  direction  whereby  the  cylindrical  formers  are  pressed,  either 
simply  by  centrifugal  force  or  by  any  other  method  the  precipitate 


Fig-  47- 


is  smoothed  out  in  the  same  manner  as  if  the  forming  plates  were 
plane.    The  apparatus  of  Fig.  47  is  constructed  similarly  with  the 


slight  additions  that  the  cylindrical  forming  plates  are  placed  ver- 
tical and  the  cylinders  travelling  over  them  are  placed  inside. 


100 


MANUFACTURE  OF  METALLIC  OBJECTS 


A  radial  arrangement  of  the  cylindrical  rollers  upon  a  concen- 
trically moulded  forming  disk  is  shown  in  Fig.  48.    In  Fig.  49  the 


Fig.  49. 

forming  of  the  precipitate  upon  the  inner  and  outer  surfaces  of 
the  two  hollow  forming  cylinders  is  shown,  in  which  internal 
rollers  w  and  an  external  forming  plate  p  are  used.  In  this  case 
two  anodes  must  be  used,  an  inner  and  an  outer,  marked  a  and  b. 

Advantages  and  Applications. 

The  advantages  of  the  Klein  process  are  evident  without  further 
discussion.  It  requires  a  minimum  of  space  and  a  small  amount 
of  electrolyte.  It  is  able  to  produce  any  described  article  having 
for  its  outlines  a  surface  of  revolution,  which  is  not  the  case  if  the 
cylindrical  formers  are  used  without  the  aid  of  the  smoothing  or 
forming  plates. 

The  process  is  very  suitable  for  many  purposes  and  experiments 
have  been  made  to  produce  by  it  corrugated  boiler  tubes.  Since 
the  most  various  profiles  can  be  obtained  in  this  way  the  Klein 
process  has  decided  advantages  over  the  many  methods  for  the 
production  of  tubes. 

NUSSBAUM'S  PROCESS. 

The  process  of  A.  Nussbaum,1  consists  in  the  manufacture  of 
copper  vessels  and  the  like  using  a  fluid  under  pressure  between 
the  deposit  and  the  mould.  This  is  done  in  the  simplest  manner 
by  causing  the  fluid  under  pressure  to  pass  through  a  valve-like 
arrangement  at  the  inner  surface  of  the  deposit  and  to  raise  up  the 
latter  and  pass  between  it  and  the  mould ;  the  electrolytic  deposit 
is  extended  at  one  side  of  the  mould  into  a  nipple  by  means  of  a 

1  German  Patent  91,146,  May  28,  1896  ;  see  also  Engelhardt :  III  Interuationaler  Congr. 
f.  angew.  Chemie  :  Chem.  Zeitg,  22,649,  (1898). 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE 


101 


bolt  or  protuberance  in  the  mould  which  on  being  screwed  out 
leaves  a  tube  which  serves  as  a  means  of  introducing  the  fluid 
under  pressure  between  the  deposit  and  the  mould. 

The  apparatus  for  the  practical  carrying  out  of  the  process  is 
shown  in  the  accompanying  figures. 

Figures  50-54  show  the  mould  with  the  valve  v  which  is  then 
coated  with  the  deposit  u.  Fluid  under  pressure  is  then  pumped 

Fig.  50.  Fig.  52. 


Fig-  53-  Fig-  54- 

into  the  center  of  the  hollow  mould  or  best  by  nieans  of  the  pres- 
sure tube  n,  where  it  lifts  the  valve  v  at  the  surface  of  the  mould. 
The  pumping  in  of  the  fluid  must  proceed  slowly  at  first  in  order 
to  give  it  time  to  insinuate  itself  between  the  surface  of  the  mould 
and  the  precipitate  and  so  to  enlarge  the  effective  pressure  sur- 
faces; otherwise  the  precipitate  may  rupture  at  the  valve.  The 
complete  separation  of  the  precipitate  is  indicated  by  a  slight 
crackling;  with  larger  objects  several  cracklings  may  be  heard 
corresponding  to  the  loosening  of  the  different  parts.  After  a 
few  further  strokes  of  the  pump  the  precipitate  separates  from  the 
mould. 


IO2  MANUFACTURE  OF  METALLIC  OBJECTS 

The  Valve. 

The  valve  v  must  close  tightly  in  order  to  prevent  the  entrance 
of  the  fluid  under  pressure  into  the  mould  and  to  perfectly  com- 
plete the  unbroken  surface  of  the  mould.  The  best  shape  is  a 
slightly  conical  valve. 

Small  valves  keep  tight  by  simple  greasing,  larger  ones  must  be 
held  down  by  a  suitable  spring  ff  or  by  a  bent  wire  d  with  a  pro- 
jecting wedge  k  fastened  to  an  enlargement  v1  of  the  valve.  The 
spring  f  under  the  influence  of  pressure  of  the  fluid  slides  easily 
out  of  its  seat  and  thereby  leaves  the  valve  open.  The  bent  wire 
d  must  be  freed  by  the  loosening  of  the  wedges  k  before  pumping 
in  the  pressure  fluid  in  order  to  render  possible  the  pressing  out 
of  the  valve  v. 

Vessel  moulds  having  a  convex  bottom  may  be  provided  with 
smaller  valves,  but  these  require  rather  high  pressures.  Vessels 
with  flat  bottoms  must,  however,  have  valves  almost  the  size  of  the 
bottom  and  be  strong  enough  to  withstand  the  pressure  ;  otherwise 
the  flat  bottoms  will  bulge  out  or  even  burst.  In  the  manufacture 
of  open  tubes  it  is  recommended  to  make  them  with  a  hemispher- 
ical auxiliary  bottom  and  valve  because  the  convex  depositing 
surfaces  stand  the  pressure  better  which  is  necessary  for  the  re- 
moval of  the  tube. 

The  valves  are  easily  loosened  from  the  precipitate,  if  neces- 
sary, they  are  given  several  blows  with  a  wooden  hammer.  If  a 
tube  with  an  open  end  is  to  be  made  the  precipitate  at  this  end  is 
cut  off,  the  valve  inside  pushed  out.  In  making  small  tubes,  the 
tube  serving  as  the  mould  can  be  also  the  pressure  tube,  but  must 
in  this  case  have  a  greater  thickness  of  walls  than  the  precipi- 
tate. For  larger  articles  a  special  pressure  tube  is  used  in  which 
case  the  tubes  acting  as  the  moulds  can  be  made  correspondingly 
slimmer  because  they  do  not  have  to  withstand  inner  pressure.  The 
separation  and  loosening  of  the  precipitate  is  easier  in  this  case 
because  the  mould  is  somewhat  compressed  by  the  pressure  and 
the  pressure  fluid  can  more  easily  find  its  way  along  the  precipi- 
tate. 

The  Pressure  Tube. 

The  pressure  tube  is  either  fastened  permanently  to  the  mould 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE  IO3 

by  means  of  flanges  or  is  pressed  firmly  against  the  flat  bottom  of 
the  vessel  and  its  free  end  arranged  for  connection  with  the  pres- 
sure pump.  It  is  better  to  place  them  in  the  axis  of  the  mould  at 
the  bottom  of  the  same.  In  the  case  of  long  articles  in  which  the 
precipitate  cannot  be  axially  removed  from  the  mould,  several 
pressure  tubes  can  be  placed  at  suitable  distances  from  each  other. 
By  pumping  the  pressure  fluid  into  the  several  pressure  tubes  the 
precipitate  can  be  successively  removed. 

Raising  of  the  Precipitate. 

The  loosening  of  the  precipitate  is  possible,  Fig.  54,  in  the  case 
of  open  vessels  without  using  a  valve.  The  metallic  tube  is  closed 
at  its  open  end  by  means  of  an  auxiliary  piece  into  which  a  bolt 
passes.  When  a  sufficiently  thick  deposit  has  been  formed  on  the 
pressure  tube  the  auxiliary  piece  and  the  bolt,  of  which  the  head 
of  the  latter  has  been  protected  from  receiving  a  precipitate  by 
means  of  a  coating  is  then  turned  out  and  the  tubular  nipple-form 
of  the  precipitate  is  then  fastened  to  the  pressure  pump,  for  in- 
stance, by  tapping  it  with  a  screw-thread.  The  separating  of  the 
precipitate  results  as  when  using  the  valve  arrangement. 

Patent  Claims. 

1.  The  process  for  the  loosening  of  electrolytic  precipitates  by 
pumping  in  a  fluid  under  pressure  between  the  precipitate  and  the 
metallic  surface. 

2.  A  method  of  carrying  out  the  process  of  Claim  i,  charac- 
terized by  the  use  of  a  pressure  fluid  which  raises  a  valve-like 
movably  arranged  part  of  the  surface  together  with  the  precipi- 
tate thereupon  and  thereby  passing  between  the  precipitate  and 
the  mould ;  in  connection  wherewith  for  the  introduction  of  the 
pressure  fluid  the  use  of  either  a  hollow  formed  mould  itself  (w. 
Fig.  50)  or  a  particular  pressure  tube  (r,  Fig.  50  and  53)   fas- 
tened against  the  body  of  the  mould. 

3.  A  second  method  of  carrying  out  the  process  of  Claim  i,  in 
which  the  electrolytic  precipitate  is  prolonged  at  an  open  place  of 
the  mould  by  means  of  a  bolt  (b,  Fig.  54),  for  the  purpose  of  con- 
necting to  the  nipple  formed  pressure  tube  after  the  withdrawal 
of  the  bolt. 


IO4  MANUFACTURE  OF  METALLIC  OBJECTS 

As  is  shown  in  the  following  calculation  of  profits1  the  Nuss- 
baum  process  should  soon  replace  the  old  coppersmiths'  work. 

COST  OF  PLANT. 

For  a  plant  with  a  daily  output  of  900  kilograms,  or  yearly  300 
tons  of  copper  vessels  and  using  100  HP. 

(a)  Dynamo $  3,000.00 

Measuring  instruments  and  switchboard 212.50 

Main  conductors ' 87.50 

Unforseen 125.00 

Erection 337-5Q 

(b)  200  baths  with  stirring  apparatus,  without  solu- 

tions and  anodes,  at  $106.25 21,250.00 

(c)  Pumps,  lathes  and  various  tools 2,512.50 

(d)  3,000  moulds  at  $4.25 12,750.00 

(e)  8 1  tons  of  anode  copper  at  $300  per  ton 24  300.00 

(f )  Electrolyte  (CuSo4  +  H2SO4) 7,500.00 

(g)  Water-power  plant  with  turbines  at  $127. 50  per 

H.P 12,750.00 

(h)  Buildings,  1,700  square  yards  shedding 14,375.00 

200  square  yards  brick  building  .    ...  2,550.00 

5,000  square  yards  ground 2,125.00 

(i)  Purchase  of  patents 25,000.00 

(k)  Working  capital 12,500.00 

Total $141,375.00 

OPERATING  COST   (YEARLY). 

1.  Wages:     50  workmen  at  $191.25 $  9,562.50 

1  foreman ; 500.00 

2  engineers  at  $375.00 750.00 

2.  300  tons  of  electrolytic  copper  at  $300  per  ton . . .  90,000.00 
3  per  cent,  waste  of  anode  material 2,700.00 

3.  Lubricating  material,  etc . .' 450.00 

4.  Sinking  Fund. 

10  %  of  the  electrical  equipment  ($3,875) 387.50 

15  "       "       bath  equipment  ($21,250) 3,187.50 

10  "       "        machinery  equipment  ($2,512.50).  251.25 

15  "       "       cost  of  moulds  ($12,750) 1,912.50 

5  "       "       cost  of  electrolyte  ($7,500) 375-oo 

5  "       "       cost     of  '  the     water-power    plant 

($12,750) 637.50 

4  "       "        building  cost  ($19,050) 762.00 

8"       "       cost  of  the  patents 2,000.00 

i  The  following  data  I  owe  to  Chief  Engineer  Engelhardt. 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE  IO5 

5.  Interest  : 

5  %  of  the  working  capital  (12,500) 625.00 

2  "       "        cost  of  the  anode  copper  (24,300).  486.00 

6.  General  expenses  : 

Superintendent $  1,250.00 

Two  clerks 1,500.00 

Insurance 250.00 

Taxes 6, 250.00 

Diverse  expenses 3,300.00 

$  12,550.00 


Total $127,136.75 

Rounded  to 1 27, 500. oo 

PROFITS. 

Assuming  the  value  of  the  300  tons  of  ware  at  $575.00 

per  ton $172,500.00 

Operating  expenses 1 27,500.00 


Yearly  profits $  45,000.00 

Corresponding  to  a  dividend  of  32  per  cent.1 

The  following  patents  are  of  smaller  importance,  but  are  put  in 
for  the  sake  of  completeness. 

SUTHERLAND'S  PROCESS. 

W.  S.  Sutherland2  precipitates  metal  upon  easily  fusible  forms, 
to  produce  surface  condensers  and  steam  generators. 

ELMORE'S  PROCESS. 

F.  E.  Elmore3  patented  a  process  for  the  manufacture  of  hollow 
•vessels  and  evaporating  pans  in  which  the  forms  were  coated  first 
with  a  layer  of  adhering  and  then  with  a  coating  of  non-adhering 
•copper.  The  forms  thus  treated  were  then  placed  upon  a  hori- 
zontal shaft  in  the  bath  and  connected  up  as  cathodes,  using  as 
anodes  either  copper  strips  or  strips  of  insoluble  material  arranged 
at  equal  distances  from  the  cathode.  The  shaft  carrying  the 
cathode  is  rotated  and  the  precipitate  is  worked  by  smoothing 
tools. 

1  The  differences  in  the  cost  of  labor  in  Europe  and  in  America  would  modify  many 

of  these  assumptions.— Translator. 
-  English  Patent  8,054,  May  22,  1884. 
3  English  Patent  10,451,  Sept.  5,  1885. 


IO6  MANUFACTURE  OF  METALLIC  OBJECTS 

PROCESS  OF  DAVIS  AND  EVANS. 

J.  W.  Davis  and  J.  O.  Evans1  produce  hollow  metallic  ware  by 
using  sectional  forms  upon  which  the  metal  is  deposited  while  the 
electrolyte  is  circulated  in  the  usual  manner. 

C.  G.  Haubold  produces  perforated  hollow  metallic  cylinders 
by  fastening  upon  the  forms  upon  which  the  metal  is  to  be  pre- 
cipitated rods  of  non-conducting  material  which  on  being  removed 
leave  a  cylinder  with  corresponding  perforations. 

PROCESS  OF  A.  KRUGER. 

Miss  A.  Kruger2  obtained  a  patent  for  the  production  of  flexible 
objects  by  the  electrolytic  precipitation  of  metal,  the  several  layers 
of  which  are  separated  either  partially  or  totally  from  each  other 
by  intermediate  layers  so  as  to  be  sufficiently  flexible  in  spite  of 
their  solidity. 

Patent  Claims. 

1.  A  process  for  the  production  of  flexible  elastic  bodies  elec- 
trolytically,  characterized  by  producing  alternately  repeated  elec- 
trolytic deposits  of  metal  and  intermediate  layers  completely  or 
partially  separating  the  metallic  layers  from  each  other. 

2.  A  method  of  carrying  out  the  process  of  Claim  i,  in  which 
the  metallic  layers  are  deposited  upon  an  elastic  support  in  order 
to  produce  greater  elasticity  of  the  coating. 

3.  The  methods  of  carrying  out  the  processes  of  Claims  i  and 
2,  in  which  the  metallic  layers  consist  o'f  different  metals  or  alloys 
in  any  desired  order  or  sequence. 

4.  A  method  of  carrying  out  the  processes  of  Claims  1-3,  in 
which  the  metallic  precipitates  are  smoothed  or  pressed  mechan- 
ically. 

The  process  consists  practically  in  the  use  of  various  electro- 
lytes and  certain  changes  and  sequences  for  the  obtaining  of 
metals  and  alloys  of  fixed  composition,  which  later  may  be  caused 
to  unite  with  each  other  by  heating,  and  the  smoothing  of  the  sur- 
face by  a  suitable  smoothing  apparatus. 

1  English  Patent  8,108,  April  20,  1892. 

2  German  Patent  95,761,  Sept.  20,  1896;  English  Patent  26,102,   Nov.  9,  1897  ;  see  also 
Zeitschrift  f.  Elektrochemie,  6,  356. 


MANUFACTURE  OF  BODIES  OF  LARGE  SIZE  1 07 

Examples  of  the  Process. 

As  examples  are  mentioned :  In  order  to  produce  a  body  with 
a  screw-like  surface  a  conical  hollow  spindle  of  metal  is  used 
which  is  provided  with  a  coating  of  graphite  mixed  with  spirits 
of  turpentine,  which  after  being  completely  dried,  is  smoothed 
over.  By  rotating  the  spindle  in  an  electrolytic  bath  a  thin  coat- 
ing is  precipitated,  which  is  smoothed  and  provided  with  a  sepa- 
rating layer.  Then  a  further  metal  coating  is  precipitated  in  the 
bath  and  the  manipulation  continued  in  this  manner  until  the  de- 
sired strength  of  deposit  is  reached.  In  case  that  a  still  greater 
strength  of  the  metal  coating  is  desirable  it  can  be  obtained  by 
having  direct  contact  of  the  separate  metallic  layers,  which  is  done 
by  drawing  well  placed  lines  through  the  separating  layer  so  that 
at  these  points  the  succeeding  metallic  deposit  comes  in  contact 
with  the  underlying  metallic  layer,  without,  however,  sensibly 
affecting  the  flexibility  of  the  whole. 


MANUFACTURE  OF  PARABOLIC 
MIRRORS. 


The  expensive  operations  required  for  the  production  of  exact 
parabolically  curved  mirrors  has  led  many  investigators  to  at- 
tempt to  produce  such  mirrors  electrolytically  in  a  cheaper  man- 
ner. 

PROCESS  OF  THE  ELMORE  GERMAN  AND  AUSTRO -HUNGARIAN 
METAL  COMPANY,  LIMITED,  AND  P.  E.  PRESCHLIN. 

Amongst  the  important  attempts  which  have  been  practically 
tried  we  may  mention  the  process  of  the  Elmore  German  and 
Austro-Hungarian  Metal  Company,  Limited,  and  P.  E.  Presch- 
lin.1 

Patent  Claims. 

1.  An  arrangement  for  the  manufacture  of  saucer-shaped  ves- 
sels electrolytically  characterized  by  placing  the  cathode,  corre- 
sponding to  the  form  of  the  vessel,  upon  an  inclined  axle,  in  order 
thereby  to  place  the  driving  gear  and  bearings  of  the  axle  outside 
of  the  bath,  while  parts  of  the  cathode  dip  into  the  bath. 

2.  In  the  arrangement  of  the  apparatus  described  in  Claim  I  a 
smoothing  tool  pressed  by  a  spring  which  by  means  of  wheels  and 
levers  moves  slowly  in  the  plane  of  the  axis  of  rotation  of  the 
cathode  in  order  to  act  upon  all  parts  of  the  concave  vessel. 

PROCESS  OF  COWPER-COLES. 

Sherard  Osborn,  Cowper-Coles  and  the  Reflector  Syndicate, 
Limited,2  have  solved  the  problem  of  manufacturing  perfect  mir- 
rors for  reflectors  in  a  most  characteristic  mannei 

Patent  Claims. 

I.  The  process  for  the  manufacture  of  hollow  minors  charac- 
terized by  covering  over  a  mould  with  a  layer  of  wax,  precipita- 
ting upon  this  layer  silver  by  a  chemical  process,  afterwards  pre- 

1  German  Patent  71.831,  April  6,  1893. 

2  German  Patent  89,249,  Feb.  26  1896  ;  English  Patent  5  600  March  16,  1895. 


MANUFACTURE;  OF  PARABOLIC  MIRRORS  109 

cipitating  upon  the  silver  a  layer  of  palladium  galvanically,  after- 
wards also  galvanically  precipitating  a  further  coating  of  copper 
or  another  suitable  metal,  while  rotating  the  form,  and  heating 
the  mirror  after  removing  from  the  form  in  order  to  alloy  the 
palladium  with  the  silver  or  treating  the  mirror  with  a  solution 
of  potassium  cyanide  or  the  like  in  order  to  remove  the  silver. 

2.  In  the  process  described  in  Claim  i,  the  production  of  the 
wax  coating  by  painting  with  a  solution  of  wax  in  benzine  or  any 
other  volatile  solvent. 

3.  In  the  process  of  Claim  I,  rubbing  and  polishing  the  silver 
coating  before  the  galvanic  precipitation  of  the  palladium. 

4.  In  the  process  of  Claim  I,  the  use  of  a  form  consisting  of  a 
mixture  of  sulphur  and  graphite  in  which  the  latter  material  is 
somewhat  in  excess. 

The  Forms  and  Their  Manufacture. 

Forms  are  made  out  of  glass,  wax,  metal,  or  any  other  suitable 
material  which  may  be  provided  with  a  thin  coating  of  silver.  It 
must  be  noted  that  the  silver  coating  can  be  directly  precipitated 
upon  the  wax ;  all  other  kinds  of  forms  must  be  first  coated  with 
a  layer  of  wax  before  they  can  be  silvered.  The  wax  solution  is 
best  as  a  solution  of  bees-wax  in  benzine,  because  the  latter  vola- 
tilizes very  rapidly  and  leaves  the  dissolved  wax  upon  the  form  in 
an  unusually  uniform  layer.  When  this  coating  has  become  suffi- 
ciently solid  it  is  rubbed  with  a  piece  of  chamois  leather  until  it 
has  a  high  polished  surface.  This  treatment  is  quite  necessary 
with  glass  forms  since  the  small  flaws  found  upon  the  surface  of 
the  same  will  easily  become  larger  by  use,  and  they  cause  the 
formation  of  still  larger  unevenness  if  they  are  not  carefully  cov- 
ered over. 

The  silver  precipitate  produced  in  the  chemical  way  is  likewise 
rubbed  and  polished  with  leather,  whereby  at  the  same  time  the 
silver  is  loosened  from  the  support.  The  silvered  form  is  then 
covered  over  with  palladium  in  a  galvanic  bath  consisting  of 

Palladium  ammonium  Chloride 0.62  per  cent. 

Ammonium  chloride 1 .00         ' ' 

The  bath  is  worked  at  a  temperature  of  24°  C.,  using  graphite 
plates  for  anodes.  The  current  density  used  is  0.027  ampere  per 


HO  MANUFACTURE  OF  METALLIC  OBJECTS 

square  decimeter,  the  bath  tension  corresponding  to  the  feeble 
concentration  of  4  to  5  volts. 

The  silver  bath  for  coating  the  wax  consists  of 

Silver  nitrate 0.5  per  cent. 

Caustic  potash 0.5         " 

Glucose 0.25       " 

The  form  being  thus  prepared  it  is  placed  in  a  copper  bath  con- 
taining : 

Water 83  parts 

Copper  sulphate 13     " 

Sulphuric  acid 3     " 

At  starting  a  high  current  density  is  used  up  to  10  volts  ten- 
sion. The  palladium  layer  is  covered  over  very  quickly  with  cop- 
per and  then  the  current  density  is  decreased.  During  the  precipi- 
tation of  copper  the  form  is  continually  rotated  and  the  precipi- 
tate may  be  smoothed  by  smoothing  tools  while  it  is  forming. 

Loosening  of  the  Precipitate. 

When  the  copper  backing  has  reached  the  desired  thickness  the 
form  with  its  silver,  palladium  and  copper  precipitates  is  removed 
from  the  bath  and  warmed  to  between  65°  and  95°  C.,  whereupon 
the  layer  of  wax  melts  and  the  form  is  separated  from  the  pre- 
cipitate. The  precipitate  is  now  further  heated  in  order  that  the 
silver  may  alloy  with  the  palladium,  or  the  silver  coating  is  treated 
with  a  solution  of  potassium  cyanide  or  some  other  solvent  of  sil- 
ver which  does  not  attack  the  palladium. 

In  the  first  case  the  mirror  will  have  a  surface  consisting  of  a 
palladium-silver  alloy  which  has  the  advantage  that  the  palladium 
is  not  so  easily  tarnished  as  the  silver  while  the  silver  gives  to  the 
precipitate  a  high  lustre. 

If,  on  the  other  hand,  the  silver  is  completely  dissolved  away 
then  a  pure  palladium  surface  is  left,  which  likewise  shows  a  high 
lustre  because  it  was  produced  upon  a  polished  silver  background. 
Instead  of  precipitating  the  palladium  upon  the  silver  and  copper 
upon  the  palladium  the  copper  can  be  precipitated  immediately 
upon  the  silver,  and  the  palladium  or  any  other  non-tarnishing 
metal  precipitated  upon  the  silver  after  the  removal  of  the  mirror 
from  the  form. 


MANUFACTURE   OF   PARABOLIC    MIRRORS  III 

If  the  form  is  of  metal,  for  instance  of  iron,  with  a  layer  of  cop- 
per silvered  upon  its  surface,  the  palladium  can  at  once  be  pre- 
cipitated upon  its  surface  without  first  coating  it  with  silver ;  the 
copper  can  also  be  precipitated  immediately  upon  the  form  having 
a  silver  coating. 

Chromium  may  serve  as  a  substitute  of  palladium  or  silver  in 
the  manufacture  of  spherical  mirrors. 

The  economy  of  the  manufacture  of  mirrors  by  the  above  de- 
scribed process  consists  principally  that  the  reflectors  do  not  need 
tedious  polishing  but  at  the  most  need  a  treatment  such  as  is 
called  in  practical  galvanoplasty,  "Hand  coloring."  At  the  same 
time  the  mirror  surfaces  are  produced  nearer  to  the  mathemati- 
cally correct  shape  than  by  the  previously  used  process.  Finally 
the  new  mirrors  are  less  sensitive  to  deformation  by  uneven  heat- 
ing and  are  not  so  easily  injured  by  rough  handling. 

If  desired  the  reflectors  can  also  be  made  hollow  so  that  water 
or  any  fluid  may  be  run  through  them  to  avoid  too  high  heating 
when  in  use  or  the  alteration  of  shape  which  is  caused  by  heating 
may  be  compensated  for  by  unequal  thickness  of  the  walls  of  the 
reflector. 

The  forms  are  made  preferably  of  a  mixture  of  sulphur  and 
graphite,  with  the  latter  somewhat  in  excess,  and  may  be  cast  in 
glass  moulds. 

The  palladium  or  palladium  alloy  can  also  be  placed  upon  the 
mirror  in  the  form  of  an  amalgam,  for  instance,  by  a  similar  pro- 
cess to  that  used  in  gilding  with  mercury. 

Apparatus. 

The  patent  specification  describes  a  series  of  apparatus  particu- 
larly for  the  carrying  out  of  the  electrolytic  part  of  the  work. 
Fig.  55  shows  a  longitudinal  section  of  an  electrolytic  bath  on 
which  the  copper  background  of  the  mirror  is  deposited. 

Figs.  56-58  show  the  details  of  the  apparatus. 

Inside  the  box  A  is  the  form  B  serving  as  cathode  and  provided 
with  an  edge  B1  and  arranged  so  as  to  be  removable  from  but 
resting  upon  the  square  upper  end  of  a  vertical  shaft  b,  which  is 
rotated  by  conical  wheels  beneath  through  the  journal  C  and  the 
packing  box  D.  The  anode  E  has  an  arched  form  corresponding 


112 


MANUFACTURE  OF  METALLIC  OBJECTS 


to  the  form  B  and  may  be  hung  in  the  eye  e  in  any  convenient 
manner.  It  is  covered  inside  with  a  woven  cover,  for  instance  of 
unbleached  cotton,  in  order  that  any  small  particles  from  the 
anode  may  not  fall  upon  the  form.  During  the  rotation  of  the 
form  B  the  roller  G4,  which  is  coupled  by  an  arm  G3  to  an  arm 
G!,  produces  pressure  upon  the  copper  precipitate.  This  latter  lies 
removable  in  the  yoke  G,  held  there  by  the  eye  G2,  the  end  being 
movable  backwards  and  forwards  by  the  endless  screw  F1,  placed 


Figs.  55,  56,  57,  58. 

upon  an  axle  F.  The  axle  F  is  fixed  upon  the  box  A  by  the  bear- 
ings /  and  carries  at  one  end  three  disks  f-f  f2,  fz,  of  which  the 
middle  one  is  loose  and  driven  by  one  crossed  and  one  straight 
belt.  The  belt  fork,  G9,  which  governs  the  position  of  both  belts, 
is  fastened  to  a  bent  lever,  G7,  by  means  of  a  rod,  G8,  and  in  the 
same  manner  as  the  upward  directed  arm,  G5  moves  the  nut  G 
upon  the  rod,  G6,  which  is  fastened  above  the  shaft  F. 


MANUFACTURE  OF    PARABOLIC    MIRRORS  1 13 

By  the  arrangement  described  the  direction  of  rotation  of  the 
shaft  F  is  periodically  automatically  reversed,  since  the  nut  G 
moved  in  one  direction  by  the  screw  F1  strikes  against  the  end  of 
the  bent  lever,  G7,  with  its  arm,  G5,  and  moves  with  it  until  the 
belt  reversing  motion  is  operated;  whereupon  the  screw  moves 
in  the  opposite  direction  until  the  arm,  G5,  strikes  against  the 
other  end  of  the  bent  lever  and  again  reverses  the  belts.  The 
arm,  G1,  moves  with  the  motion  of  the  nut,  G,  since  it  passes  into 
the  slit,  E2,  of  the  anode  E,  while  the  roller,  G4,  moves  up  to  the 
.apex  of  the  form. 


Fig-  59- 

In  order  that  the  roller,  G4,  may  regulate  automatically  the 
pressure  which  it  exerts  against  the  top  of  the  copper  precipitate 
corresponding  to  the  circular  part  of  the  mirror  upon  which  it 
works,  the  arm,  G3,  is  provided  with  a  weight,  H,  which  is  car- 
ried in  a  slit,  g,  and  has  an  automatic  motion  imparted  to  it  by  the 
arrangement  shown  in  Figs.  56-58.  The  threaded  part,  F1,  of  the 
shaft  F  engages  the  worm  wheel,  o4^  which  is  keyed  to  the  nut  G, 
and  upon  whose  axle  a  roller,^3,  alternately  winds  and  unwinds  a 
chain  or  a  string,  g1,  which  is  carried  over  an  idler,  g2,  to  the  rod 
of  the  balance  weight,  H,  and  thus  moves  it  up  and  down  as  the 
shaft,  F,  is  turned  in  one  or  the  other  direction. 

In  Fig.  59  there  is  shown  a  somewhat  different  arrangement. 
The  cupola-shaped  anode  is  replaced  by  two  plate-like  forms. 
Two  rollers,  G4,  are  placed  diametrically  opposite  each  other  in 
the  arms  I2  and  I3  loaded  by  the  weights  \*x  and  P.r.  Both  arms 


1 14  MANUFACTURE  OF  METALLIC  OBJECTS 

are  connected  to  the  nut,  I1,  which  is  moved  up  and  down  by  the 
vertical  spindle,  I,  whereby  the  rollers,  G4,  approach  almost  to 
touching  each  other  at  the  apex  and  can  separate  towards  the 
periphery  of  the  form.  The  nut,  I1,  is  hindered  from  turning  by 
the  rod  I4,  which  may  be  arranged  to  be  revolvable  around  the 
drum,  I5,  fixed  upon  the  box  A,  so  that  the  whole  arrangement 
may  be  swung  to  one  side  if  the  form  b  is  to  be  taken  out. 


Fig.  60. 


Fig.  6 1  shows  another  arrangement  which  can  be  used  in  place 
of  that  in  Fig.  59.  The  bent  arm  J  is  fastened  to  the  side  of  the 
containing  vessel  at  J1,  its  upper  end  being  held  by  an  adjustable 
brace,  J2 ;  its  outer  form  corresponds  to  that  of  the  mould  B.  Two 


Fig.  61. 


chain  rollers,  J3  and  J4,  are  fastened  to  the  ends  of  J,  one  of  which 
is  provided  with  a  driving  sheave,  and  carry  the  chain,  J5,  upon 
which  are  a  number  of  rollers,  J6,  replacing  the  pressure  roller, 
G4.  The  arm  J  carries  a  guide  for  the  chain  and  the  pressure 


MANUFACTURE  OF   PARABOLIC    MIRRORS  115 

rollers,  J6,  roll  one  after  the  other  upon  the  form  B,  each  de- 
scribing a  path  from  the  periphery  to  the  crown  of  the  mould. 

The  carriers  for  the  roller  axles  are  so  arranged  that  they  can 
be  easily  removed  if  the  mould  or  the  completed  mirror  is  to  be 
taken  out.  The  pressure  rollers  can  also  be  moved  by  little  fin- 
gers or  eccentrics,  especially  if  the  distance  between  the  periphery 
and  crown  of  the  mould  is  divided  between  several  rollers. 

A  suitable  arrangement  is  also  that  of  inclining  the  shaft  B, 
and  giving  the  box  an  angular  cross-section  in  such  manner  that 
one  wall  is  at  right  angles  to  the  shaft.  The  shaft  B  can  also  be 
made  telescopic  and  provided  with  a  screw  arrangement  or  the 
like  to  allow  of  the  form  being  lifted  out  of  the  box. 

The  observation  of  the  precipitate  is  facilitated  if  the  vessel  is 
connected  by  means  of  a  hose  with  another  vessel  so  that  by  the 
raising  or  lowering  of  the  latter  the  solution  can  be  run  in  or  run 
out  of  the  precipitating  box. 


Fig.  62. 

Fig.  62  shows  an  apparatus  suitable  for  the  precipitating  of  a 
galvanic  coating  of  palladium  or  chromium  upon  the  form.  The 
pan  K  is  heated  with  steam  and  lined  with  lead  or  some  other 
metal  suitable  as  an  anode  and  which  will  hold  the  palladium 
solution.  It  is  carried  by  a  spindle  L,  which  since  it  is  prevented 
from  rotating  by  the  steam  pipe  may  be  raised  or  lowered  by 


Il6  MANUFACTURE  OF  METALLIC  OBJECTS 

means  of  the  nut  M  turning  in  the  bearing  O,  so  that  the  form  B 
fastened  by  means  of  hooks  N2  and  the  chain  N1  to  the  supports 
N,  can  be  dipped  into  the  solution  by  the  raising  of  the  pan  K  or 
left  out  of  the  solution  by  the  lowering  of  the  same.  With  this 
arrangement  a  comparatively  small  quantity  of  palladium  solu- 
tion is  necessary  for  constituting  the  bath. 

Instead  of  the  forms  as  shown  in  Figs.  55-61  with  their  bent 
surfaces  arranged  on  top,  these  may  be  inverted  and  driven  by 
vertical  shafts  from  above.  In  these  cases  the  round  anode  and 
the  pressure  rollers  can  be  dispensed  with  and  replaced  by  the 
pressure  of  the  friction  between  the  surface  of  the  rotating  form 
and  the  electrolyte. 

This  process  is  carried  out  on  a  large  scale  by  the  "Searchlight 
Syndicate,  Limited,"1  who  manufacture  parabolic  mirrors  and 
locomotive  headlights.  Several  reflectors  are  precipitated  and 
taken  from  one  form  without  the  latter  needing  polishing.  The 
process  is  not  expensive.  For  instance,  the  silver  deposit  does 
not  weigh  more  than  0.059  milligram  per  square  inch  and  is 
0.0000034  inch  thick.  The  cost  of  this  deposit  is  not  more  than 
2  3/2  to  4  cents  per  square  inch. 

1  The  Electrician,  L,ondon,  (46),  578  to  580. 


Xin.    MANUFACTURE   OF  TUBES. 


In  the  processes  coming  under  this  heading  the  most  necessary 
items  are  suitable  arrangements  to  separate  the  metal  deposited 
upon  suitable  mandrils  from  the  same,  and  to  obtain  an  outer  sur- 
face smooth  and  free  from  excrescences. 

Elmore  has  succeeded  in  this  line  quite  brilliantly,  producing 
on  a  larger  scale  tubes  of  the  most  varying  diameters  and  lengths. 

For  the  quick  production  of  tubes  of  small  diameter,  J.  O.  S. 
Elmore1  uses  the  following  apparatus  suitable  for  continuous 
working  (Figs.  63-66)  : 

The  bath  is  contained  in  a  trough  shaped  vessel  A,  having  a 
[/-shaped  section  and  divided  by  partitions  into  a  number  of 
chambers  through  which  the  core  D  passes.  In  some  of  these 


K  F 


D  A 

Figs.  63,  64,  65,  66. 

subdivisions  the  electric  current  is  led  to  the  core^  by  springs  C 
and  the  precipitate  is  rubbed  by  polishing  stones  B.  The  anodes 
are  only  placed  in  such  compartments  which  contain  neither  con- 
tact places  or  smoothing -tools,  thus  avoiding  the  plating  of  these 
parts. 

The  trough  is  longer  than  a  single  core  which  latter  extends 
between  two  rods  of  non-conducting  material  such  as  wood  or 
the  like.  It  is  passed  through  the  end  of  the  box  by  means  of 
stuffing  boxes  H. 

1  German  Patent  95,857,  July  2,  1897  ;  English  Patent  7,222,  April  2.  1896. 


n8 


MANUFACTURE  OF  METALLIC  OBJECTS 


The  electrolyte  flows  continuously  through  the  apparatus  and 
the  trough  is  covered  with  a  closely  fitting  cover  R  in  order  that 
the  electrolyte  may  be  conducted  through  it  under  pressure.  The 
core  is  rotated  during  the  action  of  the  process  and  moves  in  and 
out  through  the  chambers. 

Patent  Claims. 

i.  The  apparatus  for  the  manufacture  of  tubes  by  electrolytic 
deposition  of  metal,  characterized  by  using  a  box  A  divided  into 
chambers  with  a  rotating  core  or  mandril  D,  serving  as  a  cathode 


Fig.  67. 

and  movable  backwards  and  forwards  in  the  direction  of  its 
length  and  provided  with  contact  springs  C  and  smoothing  tools 
e,  in  some  of  the  compartments,  and  with  anodes  f  of  the  metal 
to  be  precipitated  surrounding  the  anode  in  the  alternate  com- 
partments, in  such  manner  that  the  electrical  current  passes 
through  the  contacts  C  and  the  anodes,  decomposing  the  electro- 
lyte flowing  through  the  compartment  and  depositing  the  metal 
upon  the  core. 


MANUFACTURE  OF  TUBES  119 

2.  The  form  of  apparatus  for  carrying  out  Claim  i,  in  which 
a  series  of  vessels  A  have  their  cores  or  mandrils  insulated  from 
each  other  by  the  insertion  of  non-conducting  pieces,  and  the 
anode  of  each  box  is  in  electrical  connection  with  the  contact 
springs  bearing  upon  the  mandril  of  the  next  following  box,  thus 
making  it  possible  to  remove  from  time  to  time  the  last  mandril, 
to  move  up  the  following  mandril  into  the  last  box  and  to  place 
a  polished  mandril  in  the  first  box  and  so  to  produce  tubes  con- 
tinuously. 

Old  Process  of  1890. 

The  old  process1  for  the  manufacture  of  tubes  had  the  following 
patent  claims. 

i.  The  process  of  producing  copper  tubes  electrolytically  con- 
sisting in  placing  the  iron  mandril  first  in  a  copper  cyanide  bath 
and  coating  it  with  a  layer  of  copper  which  is  afterwards  oxidiz- 
ed and  subsequently  placed  in  an  -acid  solution  of  copper  sulphate 
for  the  purpose  of  further  precipitating  and  compressing  of  the 
copper ;  using  in  the  latter  bath  copper  plates  with  granulated  cop- 


per  thereupon  as  anodes,  and  rotating  the  mandril   serving  as 
cathode,  while  at  the  same  time  the  precipitated  layer  of  copper  is 

1  German  Patent  59,933,  Nov.  19,  1890 ;  English  Patent  18,896,  Nov.  21,  1890  ;  American 
Patent  464,351  ;  French  Patent  209,602, 


I2O  MANUFACTURE  OF  METALLIC  OBJECTS 

compressed  by  an  oscillating  polishing  tool,  and  finally  subjecting 
the  mandril  thus  coated  to  the  influence  of  pressure  rollers  in  such 
manner  that  the  copper  coating  is  stretched  in  the  direction  of  its 
circumference,  and  thus  loosened  from  the  mandril. 

2.  The  modification  of  the  process  of  Claim   I,  consisting  in 
afterwards  plating  a  certain  thickness  of  copper,  in  order  to  form 
separated  concentric  copper  tubes  one  over  the  other. 

3.  For  the  carrying  out  of  the  process  of  Claim  I,  the  use  of 
two  parallel  series  of  electrolytic  baths  with  mandrils  therein,  the 
rotation  of  which  is  accomplished  by  means  of  an  intermediate 
shaft,  while  the  backwards  and  forwards  motion  of  the  polishing 
tools  is  produced  over  all  the  mandrils  simultaneously  by  means 
of  a  reversing  pulley  and  coupling  actuated  by  a  finger  fastened 
upon  a  spindle  of  the  first  pair  of  mandrils. 

4.  The  carrying  out  of  the  process  described  in  Claim  i,  con- 
sisting in  the  loosening  of  the  copper  tubes  from  the  iron  mandril 
by  placing  the  mandrils  between  concentric   rollers  and  slowly 
rotating  the  same  while  at  the  same  time  pressure  rollers  T1,  T2, 
T3,  normal  to  the  tube  exert  pressure  upon  the  copper  tube  and 
are  movable  in  the  direction  of  the  length  of  the  tube. 

The  Polishing  Tools. 

The  Elmore  process  lays  particular  stress  upon  the  construction 
of  the  polishing  tools  and  they  patent  several  different  forms.  The 
Elmore  German  and  Austro-Hungarian  Metal  Company,  Lim- 
ited, makes  the  smoothing  tools  in  the  shape  of  a  wheel  rotating 
upon  an  axis,  which  is  approximately  perpendicular  to  the  ro- 
tating mandril.  The  wheel  is  moved  the  length  of  the  mandril 
backwards  and  forwards,  and  at  the  same  time  has  a  rotary  mo- 
tion. As  soon  as  the  surface  of  the  precipitated  metal  becomes 
uneven  the  smoothing  wheel  must  have  a  radius  which  is  smaller 
than  the  smallest  radius  of  any  of  the  depressions  in  the  coating. 
The  wheel  can  then  enter  into  any  cavity  and  work  its  surface. 
Fig.  68  shows  a  section  through  the  bath  in  which  the  wheel- 
formed  smoothing  tool  acts  upon  the  rotating  mandril  M.  A  is 
an  arm  provided  with  a  screw  spindle  which  moves  it  backwards 
and  forwards  parallel  to  the  axis  of  the  mandril.  The  smoothing 
tool  is  then  moved  backwards  and  forwards  upon  the  metallic  stir- 


MANUFACTURE  OF  TUBES  121 

face  of  the  deposit.  A  clamping  screw  fastens  the  second  arm  B 
to  the  bracket  A  by  a  slot  in  the  latter  and  the  rod  R,  which  is 
movable  by  means  of  the  screw  S.  The  rod  R  is  fork-shaped  and 
carries  the  wheel  W,  which  with  one  edge  runs  upon  the  surface 
of  the  mandril.  A  rubber  band  C  passing  around  the  rod  R  and 
into  the  teeth  upon  the  arm  B,  serves  to  press  tne  wheel  W  against 
the  circumference  of  the  mandril. 

Since  the  arm  B  moves  back  and  forth  upon  the  mandril  the 
wheel  W  passes  along  the  latter  and  continually  forces  its  edge 
to  the  smoothing  of  new  deposits.  When  one  of  these  edges  is 
.dulled  the  wheel  is  turned  around  the  axle  of  the  rod  R  in  order 
to  use  the  other  edge.  A  positive  motion  can  be  given  to  the  wheel 
W  by  means  of  a  wire  or  a  cord  running  around  a  small  pulley 
upon  the  same  axle  and  so  give  to  the  wheel  a  quicker  or  slower 
motion  than  it  would  naturally  acquire  from  its  contact  with  the 
copper  tube.  The  driving  wire  or  cord  is  stretched  the  whole 
length  of  the  bath  and  is  kept  tight  by  a  weight  so  that  it  con- 
tinually presses  against  the  small  pulley  and  thus  rotates  the  wheel 
W. 

Patent  Claim. 

An  arrangement  for  the  smoothing  and  compressing  of  metals, 
which  are  being  precipitated  upon  a  rotating  mandril  character- 
ized by  using  a  wheel  of  agate  or  a  material  of  approximately 
equal  hardness  which  is  pressed  against  the  mandril  with  one  edge 
while  the  latter  is  rotated  and  simultaneously  moved  backwards 
and  forwards  along  the  tube. 

An  alteration  in  the  manner  of  smoothing1  is  obtained  by  giv- 
ing to  the  smoothing  tools  an  additional  motion  lengthwise. 
Patents  of  Elmore. 

Further  improvements  in  the  Elmore  process  are  contained  in 
the  following  patents; 

English  Patent,  2,618,  February  14,  1889. 

German  Patent,  65,808,  April  12,  1891. 

German  Patent,  72,195,  April  6,  1893. 

German  Patent,  71,811,  April  14,  1893. 

German  Patent,  77,745,  March  4,  1894. 

1  German  Patent  67,947,  Sept.  29,  1892  ;  English  Patent  17,631,  Oct.  15,  1891  ;  American 
Patent  503,076. 


122  MANUFACTURE:  OF  METALLIC  OBJECTS 

Literature. 
The  following  articles  contain  additional  information: 

El.    (1888),  22,  47- 

Lum.  el.  (1888),  30,  435 ;  31,  280;  32,  579. 
Engineering  (1898),  No.  1714,  William  Brown. 
El.  Rev.  (1891),  28,  449  and  476.    Watt. 
Engineering  (1890),  50,  21  and  46.    A.  W.  Kennedy. 

Operation. 

In  the  manufacture  of  1,000  kilograms  of  copper  tubes  there 
are  used  1,170  kilograms  of  coal,  for  a  bath  tension  of  0.5  volts, 
corresponding  to  a  cost  of  about  $1.75. 

At  the  works  of  the  Elmore  Company  in  Hunsled,  near  Leeds, 
there  are  four  dynamos  each  of  37.5  kilowatts  and  furnishing  50 
volts  and  750  amperes. 

These  works  use  Chili  copper  granulated  by  running  into 
water.  The  plant  contains  60  baths  in  series  each  of  the  dimen- 
sions, 3  meters  long,  0.8  meter  wide  and  I  meter  deep.  The  bath 
tension  is  0.9  volt.  The  precipitate  grows  slowly  so  that  working 
night  and  day  a  copper  tube  of  0.3  millimeter  thickness  requires 
6  days  for  its  production.  In  the  works  of  the  German  Elmore 
Company  in  Sladern,  on  the  Sieg,  there  are  1,200  HP.,  of  which 
550  are  used.  The  dynamos  furnish  1,200  amperes  at  50  volts. 
The  works  can  produce  35  tons  of  tubes  weekly.  Atmer  gives 
some  exact  figures  of  the  profits  of  this  process  using  94  to  96  per 
cent,  blister  copper.  The  granules  are  used  in  a  layer  20  centi- 
meters thick  upon  the  anode  plate.  The  tanks  are  arranged  in 
long  double  rows  in  series.  Every  two  rows  of  tanks  possess  a 
common  shaft  serving  for  the  driving  of  the  mandrils.  Between 
the  tanks  of  each  row  are  cast  iron  slides  lengthwise  of  the  boxes 
and  an  automatic  mechanism  moving  in  slots  in  these  guides  pro- 
vides the  necessary  motion  for  the  smoothing  tools. 

The  copper  tubes  increase  in  thickness  0.03  of  a  millimeter  be- 
tween each  passage  of  the  agate  smoothing  tools,  thus  obviating 
the  precipitation  of  crystalline  copper.  The  advantage  of  the 
smoothing  tools  is  in  the  fact  that  using  them,  current  densities 
up  to  i  ,000  amperes  per  square  meter  can  be  employed.  The  nor- 
mal current  density  on  the  other  hand  is  scarcely  200  amperes. 


MANUFACTURE  OF  TUBES 


123 


The  normal  length  of  the  tubes  is  three  meters  and  the  process 
must  never  be  interrupted  during  the  formation  of  a  tube. 

The  tube  being  ready  the  box  containing  it  must  be  cut  onf  of 
the  circuit,  and  the  solution  run  into  a  tank  at  a  lower  level  in 
which  the  anode  slime  is  allowed  to  settle. 
Loosening  of  the  Tube. 

The  loosening  of  the  tubes  which  are  made  up  to  diameters  of 
1.6  meters  is  either  accomplished  in  the  previously  described  vva) 
or  in  case  copper  mandrils  are  used  by  substituting  for  a  period  of 
half  an  hour,  for  the  polishing  agate,  as  long  as  the  precipitate 
is  still  quite  thin,  an  agate  roller  which  rolls  upon  the  precipitate 
with  a  moderate  pressure  and  thus  loosens  it  from  the  mandiil. 

Large  copper  sheets  can  be  obtained  by  the  Elmore  proce"^  by 
cutting  a  cylinder  parallel  to  the  axis  of  the  mandril.  The  table 
in  the  Appendix  gives  data  concerning  the  weight  of  tubes  thus 
produced. 

PROCESS  OF  THE  FRENCH  COPPER  SOCIETY. 

The  Societe  des  Cuivres  de  France1  produces  compact  tubes 
electrolytically. 

The  smoothing  and  compressing  is  attained  in  this  process  by 
using  in  place  of  the  agate  tools  of  the  Elmore  process  the  pres- 
sure of  two  rollers  moving  upon  each  other. 


e-ii 


Fig.  69. 

Apparatus. 

The  apparatus  used  for  this  precipitation  is  shown  in  Figs  69- 
71.  The  container  a  holds  the  electrolytic  bath  and  has  the  roll- 
formed  cathodes  b  and  c  contained  in  any  suitable  number  in  the 

1  German  Patent  81,648,  April  7,  1894  ;   English  Patent  23,680,  Dec.  5,  1894 ;  American 
Patent  538,359,  April  30,  1895. 


124 


MANUFACTURE  OF  METALLIC  OBJECTS 


vessel.  The  lower  roller  b  has  its  axle  supported  by  insulating 
blocks  d,  which  are  also  provided  with  guides  e  for  the  spindle  of 
the  upper  roll  c. 

The  lower  roll  is  driven  by  a  belt  pulley  f  and  communicates 
its  motion  to  the  upper  roll  c  which  is  held  loosely  in  the  bushing 
in  order  that  it  can  change  its  position  according  to  the  increase 
of  the  thickness  of  the  precipitate.  The  rolls  are  kept  together 
either  by  their  own  weight  or  by  springs.  At  the  beginning,  how- 
ever, the  rolls  should  not  touch  because  such  would  injure  the 
graphite  coating  upon  them.  In  order,  therefore,  to  provide  con- 
tact between  the  rolls  from  the  start  they  are  provided  with  cop- 
per disks  at  their  ends  having  a  slightly  larger  diameter  than  the 
rolls  so  that  these  come  in  contact  with  each  other  and  leave  the 
rolls  thus  uninjured. 


it— -n 


m 


Fig.  70. 


Fig.  71. 


When  a  precipitate  of  a  certain  thickness  has  formed  the  cop- 
per rings  alluded  to  are  taken  off  and  the  rolls  allowed  to  come 
in  contact  with  each  other.  The  current  is  carried  to  the  rolls  by 
brushes  h  touching  the  roll  c.  The  rolls,  instead  of  being  ar- 
ranged as  in  Fig.  69,  can  be  arranged  in  any  desired  number,  as 
in  Fig.  71. 

The  sectional  shape  of  the  anodes  k  I,  as  well  as  their  material, 
is  determined  by  the  shape  of  the  cathodes  and  by  the  material  to 
be  deposited. 

The  current  entering  at  m  and  n  precipitates  the  copper  uni- 
formly upon  the  rolls  b  and  c,  and  is  cut  off  as  soon  as  the  de- 
sired thickness  of  deposit  has  been  obtained. 


MANUFACTURE  OF  TUBES  12$ 

Large  Tubes. 

In  precipitating  larger  tubes  according  to  this  process,  two  or 
more  smaller  rolls  can  be  used  in  order  to  avoid  too  large  dimen- 
sions of  the  tanks  and  these  rolls  are  arranged  as  shown  in  Fig. 
71.  The  current  is  carried  into  one  of  the  rolls  b  by  a  brush  h, 
and  passes  to  the  rolls  c1  and  c~.  Thus  tubes  of  large  or  small 
diameter  may  be  produced  simultaneously  in  the  one  vessel. 

As  in  the  Elmore  process  the  tubes  can  be  either  used  as  such 
or  by  slitting  and  straightening  as  copper  sheets. 

Patent  Claims. 

1.  The  process  for  the  electrolytic  deposition  and  simultaneous 
compressing  of  copper  and  other  metals  characterized  by  the  use 
of  two  or  more  rotating  rollers  as  cathodes  in  such  manner  that 
they  exert  pressure  upon  each  other  in  order  to  compress  the  metal 
precipitating  upon  them. 

2.  The  apparatus  for  carrying  out  the  process  of  Claim  i,  con- 
sisting of  a  vessel  a,  in  which  adjacent  or  superposed  rolls,  c,  or 
b,  c*-,  c2,  always  in  light  contact  with  each  other,  are  arranged  as 
rotating  cathodes,  their  distances  from  each  other  being  auto- 
matically regulated  according  to  the  thickness  of  the  metal  de- 
posit, and  the  anodes  have  any  suitable  form. 

PROCESS  OF  DUMOULIN. 

The  Dumoulin  process1  was  discovered  in  1895,  in  an  attempt 
to  find  a  suitable  method  of  avoiding  the  excrescences  upon  an 
electrolytic  deposit.  Dumoulin  observed,  as  many  others  have 
likewise,  that  the  deposition  of  metal  occurred  principally  on  the 
projecting  parts  of  the  cathode  and  that  these  excrescences  were 
the  principal  reason  that  ordinary  cathode  copper  cannot  be  rolled. 
If  the  projecting  excrescences  are,  however,  insulated  until  the 
surrounding  part  has  reached  the  same  thickness,  or  if  a  dia- 
phragm is  interposed  between  the  excrescences  and  the  solution, 
then  the  precipitation  will  finally  arrive  at  a  point  where  again 
the  smooth  surface  begins  to  be  deposited  upon. 

Dumoulin  obtains  this  hindering  of  precipitation  upon  the  ex- 
crescences by  bringing  the  cathode  cylinder  into  contact  with  an 

i  German  Patent  84,834,  April  9,  1895 ;  English  Patent  16,360,  Aug.  31,  1895;  Zeitschr.  f. 
Elektrochemie,  2,  509. 


126 


MANUFACTURE  OF  METAUJC  OBJECTS 


insulating  or  adhesive  material  placed  upon  a  porous  body.  The 
coating  of  the  body  with  insulating  material  occurs  only  upon  the 
projecting  parts,  thereby  hindering  further  deposition  upon  them. 
Fatty  substances  are  the  most  suitable  as  coating  material  or  such 
bodies  which  naturally  contain  fatty  substances  or  with  which 
such  can  be  mixed.  Amongst  these  may  be  mentioned,  animal 
membranes  and  extracts  from  them  (albumen,  fibrin,  etc.),  skins, 
muscles,  entrails,  and  the  like.  In  general,  any  sort  of  material 
may  be  used  which  is  saturated  with  a  fatty  or  oily  insulating 
body.  The  principal  requirement  is  always  that  the  body  is  pli- 
able and  does  not  fall  to  pieces  in  the  machine. 

In  the  special  treatment  proposed  by  Dumoulin,  the  following 
points  play  an  important  part : 

i.  The  contact  surfaces  of  the  cathode  and  the  rubber  holding 


u 

Fig.  72. 

the  insulating  material. 

2.  The  pressure  of  the  rubber. 

3.  The  velocity  of  motion  of  the  cathode  or  of  the  rubber. 

4.  The  current  density. 


MANUFACTURE  OF 


127 


The  rubber  is  given  a  slight  longitudinal  motion  in  order  that 
all  parts  of  the  cathode  can  be  equally  treated ;  the  movement  of 
the  rubber  is  independent  of  the  cathode  cylinder. 

The  Apparatus. 

Fig.  72  shows  in  section  the  principle  of  the  apparatus ;  it  shows 
more  particularly  a  longitudinal  section  of  the  apparatus  for  the 
manufacture  of  large  tubes  and  sheets.  The  core  m,  upon  which 
the  cathode  is  placed,  is  in  this  case  made  short.  At  the  ends  it 
has  a  pulley  g  of  insulatating  material,  and  in  the  recesses  of  the 
mandril,  there  are  rectangular  bearing  pieces  h,  which  are  con- 
nected with  the  spindle  b.  The  latter  passes  through  hollow  bear- 
ings \,  which  are  fastened  by  stuffing  boxes  to  the  vessel  A.  The 
electric  current  is  led  in  by  contact  brushes  /. 


Fig.  73. 

For  larger  tubes  the  mandril  is  of  brass  or  bronze,  for  small 
tubes  of  steel.  The  mandrils  are  polished  or  greased  before  they 
are  put  into  the  baths.  In  order  that  all  points  on  the  surface  may 
be  equally  coated  with  the  fatty  material  the  rubber  is  moved  par- 
allel to  the  length  of  the  cathode  cylinder  by  means  of  a  screw. 
This  motion  must  be  adjusted  to  the  velocity  of  rotation  of  the 
cylinder  and  be  uniform. 


128  MANUFACTURE  OF  METALLIC  OBJECTS 

The  Rubber. 

Fig.  73  shows  the  rubbing  apparatus  for  applying  the  fatty 
material.  The  latter  is  placed  in  it  and  pushed  against  the  cathode. 
The  rubbing  surfaces  are  arranged  along  side  of  each  other  upon 
a  shaft  T,  (Fig.  72),  upon  which  they  are  moved  by  a  worm  gear 
C.  They  are  movable  upon  the  shaft  T,  but  not  longitudinally. 

Dumoulin  has  the  opinion  that  the  insulating  material  can  alsa 
be  put  directly  in  the  bath;  in  this  case  the  rubbers  would  have 
*  the  function  only  of  passing  over  the  cylinder  and  rubbing  the  in- 
sulating material  upon  the  projections  of  the  cathode.     In  such 
cases  brushes  of  silk  or  the  like  would  suffice. 

Loosening  of  the  Tubes. 

The  loosening  of  the  tubes  is  attained  by  slowly  warming  them, 
whereby  the  mandrils  separate  from  the  precipitate;  if  this  is 
insufficient,  hydraulic  pressure  is  used. 

It  is  of  importance  for  the  process  that  the  temperature  does  not 
exceed  16°  C.,  in  order  to  insure  the  permanence  of  the  animal 
membranes  used.  The  temperature  can  be  kept  down  by  the 
blowing  in  of  air  and  circulation  of  the  electrolyte,  at  the  same 
time  iron  and  organic  compounds  would  be  thereby  oxidized. 

Patent  Claim. 

The  process  for  the  manufacture  of  uniform  electrolytic  metal- 
lic deposits  characterized  by  placing  upon  the  cathode  during  the 
precipitation  insulating  materials  in  such  manner  that  only  the 
projecting  parts  of  the  precipitate  receive  a  coating  of  the  in- 
sulating material,  the  process  being  in  this  respect  similar  to  the 
inking  of  type  by  ink  during  printing,  by  which  treatment  and  in 
which  process  also  the  insulating  material  is  oxidized  in  the  bath 
and  can  be  removed  by  a  rubbing  arrangement  used  for  applying 
the  insulating  material  as  soon  as  the  projecting  parts  have  dis- 
appeared and  become  uniform  with  the  whole  surface  of  the 
cathode  and  for  that  reason  do  not  need  longer  the  application 
of  the  insulating  material  for  the  retardation  of  the  deposition 
upon  them. 


MANUFACTURE:  OF  TUBES  129 

Operation. 

The  Dumotilin  process  is  carried  on  at  the  Brunoy  Works,  near 
Paris,  and  at  Widnes,  England,  by  the  Electrical  Copper  Com- 
pany, which  has  a  capital  of  $2,5OO,ooo.1 

In  the  latter  works  there  are  5  dynamos  furnishing  a  total  cur- 
rent of  1,300  amperes  at  75  volts.  The  electrolyte  used  is  a  solu- 
tion containing  40  per  cent,  of  copper  sulphate  with  7  per  cent,  of 
sulphuric  acid.  The  tanks  are  wooden  vessels  with  lead  linings 
and  the  electrolyte  circulates  through  thirty  in  series.  The  man- 
drils are  copper  cylinders  3.6  meters  long  and  40  centimeters  in 
diameter,  which  dip  half  way  into  the  electrolyte.  The  anodes  are 
of  cast  blister  copper  in  the  shape  of  a  U.  The  current  density  is 
3.5  to  4  amperes  per  square  decimeter  and  the  bath  tension  1.6 
volts. 

1  Wm.  Brown,  U1.  Rev.  (1898),  43,  561,  663.    Engineer,  Oct.  2;,  1898. 


XIV.    ELECTROLYTIC  ETCHING. 


Practical  electrochemistry  has  not  only  utilized  the  cathodic 
reactions  of  electrolysis,  but  also  anodic  reactions  in  order  to  pro- 
duce useful  articles  of  the  most  different  kinds.  The  process  of 
dissolving  metals  at  the  anode  which  is  partially  protected  or 
covered  with  a  design,  has  been  known  for  a  long  time,  and  some- 
what recently  the  process  of  Joseph  Rieders  of  electrolytically 
etching  dies  deserves  to  be  mentioned  more  at  length.  This  pro- 
cess is  called  by  the  inventor  electro-engraving,  and  is  described 
in  full  in  the  next  chapter. 

Concerning  the  ordinary  etching  processes,  such  solutions  are 
used  as  electrolytes  which  contain  free  anions,  such  as  are  able 
when  discharged  against  the  metal  of  the  anode  to  form  an  easily 
soluble  salt  therewith,  but  which  do  not  show  a  particular  tend- 
ency to  attack  the  anode  when  current  is  not  passing.  The  choice 
of  the  electrolyte  should  not  be  difficult  to  the  chemist  or  electro- 
chemist.  For  copper  or  its  alloys  dilute  sulphuric  acid  or  alka- 
line salts,  such  as  potassium  sulphate  or  potassium  nitrate;  for 
iron  and  zinc,  sodium  sulphate  or  ammonium  chloride,  for  silver 
potassium  cyanide  in  solution,  etc. 

The  procedure  in  electrolytic  etching  consists  in  coating  the 
object  to  be  etched  with  lacquer,  melted  stearine  or  some  other 
insulating  material,  laying  bare  the  parts  of  the  metal  to  be  en- 
graved or  etched,  cleaning  the  latter  with  alcohol,  benzine,  lime, 
or  any  suitable  cleaning  material,  but  in  such  a  manner  that  the  in- 
sulating coating  is  not  injured.  The  article  thus  prepared  is  used 
as  an  anode  in  the  etching  bath.  For  cathode  a  metallic  or  car- 
bon plate  is  used.  On  closing  the  circuit  the  metal  is  dissolved 
at  the  exposed  places,  while  the  covered  places  remain  imat- 
tacked.  By  regulating  the  current  it  is  possible  to  etch  more  or 
less  deeply  or  to  accelerate  the  process. 

This  method  has  many  applications ;  so  there  can  be  imagined 
an  imitation  of  deep  engraving  processes  carried  out  by  printing 
a  sample  upon  the  metallic  surface  with  a  grease  color,  in  which 


•      ELECTROLYTIC   ETCHING  13! 

case  the  fat  in  the  color  serves  as  a  coating.  The  design  which  is 
to  be  engraved  remains  uncovered.  The  printed  surface  is  then 
covered  with  powdered  asphalt  or  some  sort  of  a  resin,  some  of 
which  sticks  to  the  greasy  places  while  it  can  be  blown  away  from 
the  imprinted  places.  The  object  being  then  warmed  to  the  melt- 
ing point  of  the  resin  or  asphalt,  the  latter  melts,  and  after  cool- 
ing serves  as  a  protective  coating,  while  the  uncovered  metallic 
surfaces  are  being  etched,  so  that  in  this  way  a  deeply  cut  design 
is  obtained.  It  is  possible,  further,  to  deposit  in  the  depressions 
so  etched  a  precipitate  of  a  metal  of  different  color  from  the 
ground  mass,  and  upon  polishing  the  whole  plate  to  have  a  beau- 
tiful piece  of  inlaid  work. 

In  this  manner,  also,  may  be  produced,  without  difficulty,  plates 
and  rolls  for  calico  printing  and  embossing  of  paper,  cloth,  leath- 
er, etc.,  which  have  been  formerly  made  at  great  expense  by  en- 
graving. 


-  75-  Fig.  76. 

BURDETTE'S  PROCESS. 

Burdette1  patented  a  process  for  the  galvanic  etching,  suitable 
for  producing  figures,  monograms,  numbers,  and  other  designs 
upon  cutlery,  tableware,  etc.  Figs.  74-76  show  his  apparatus. 

1  German  Patent  83,615,  Feb.  26,  1895;  Zeitschr.  f.  Elektrochemie  2,  359. 


132  MANUFACTURE  OF  METALLIC  OBJECTS 

The  working  table  a,  usually  of  wood,  has  a  holder  b  for  re- 
ceiving the  articles  to  be  etched.  The  holder  consists  in  this  case 
of  rods  fr1  b~,  with  shallow  depressions  in  their  surfaces  for  re- 
ceiving and  holding  the  pieces.  Since  the  process  is  particularly 
intended  for  the  etching  of  cutlery,  although  it  is  applicable  for 
the  etching  of  all  other  kinds  of  metallic  objects,  its  application 
to  table  knives  is  taken  as  an  illustration. 

The  rods  fr1  b-  are  of  metal  and  insulated,  and  lie  upon  strips 
with  the  insulating  material  fastened  to  the  conductors  d.  The 
detachable  metallic  conductor  is  arranged  at  some  distance  above 
the  point  where  the  drawing  or  the  like  is  to  be  etched.  In  the 
apparatus  shown  in  Fig.  74  these  conductors  are  of  small  copper 
strips  carried  by  a  rod  f.  The  rod  f  is  fixed  to  the  arm  g,  which 
projects  from  the  stand  h,  fastened  to  the  slide  i.  The  slide  is 
fastened  to  the  conductor  k,  which  is  movable  in  relation  to  the 
row  of  knives  by  means  of  a  screw  spindle  /.  This  form  of  ap- 
paratus is  suitable  for  the  treating  of  a  number  of  pieces,  such  as 
knives,  to  produce  the  same  mark  or  design  upon  all.  For  other 
pieces  any  suitable  form  of  slide  can  be  used.  It  is  necessary 
that  the  conductor  remains  a  certain  time  immediately  above  the 
surface  of  the  piece,  being  treated  in  order  to  etch  in  the  mark 
by  the  action  of  the  electric  current. 

The  conducting  wire  m  goes  from  the  positive  pole  o  of  the 
source  of  electricity  through  the  rods  &1  b2,  upon  which  the  arti- 
cles to  be  etched  are  laid,  while  the  conducting  wire  n  from  the 
negative  pole  is  connected  with  the  rod  f  carrying  the  conductor  e. 
In  a  suitable  place,  for  instance,  along  the  front  edge  of  the  table, 
there  is  a  guide  p,  upon  which  is  fasteened  a  movable  sliding 
block  p1,  which  carries  an  adjustable  arm  with  the  stamp  q.  This 
stamp  when  pressed  down  upon  the  surface  of  the  knife-blades 
prints  upon  them  the  design  to  be  etched,  the  blades  having  been 
previously  coated  with  a  special  material :  the  surface  of  the  stamp 
is  cleaned  with  a  solution  which  will  be  described.  After  the 
articles  have  been  stamped  one  after  the  other,  the  stamp  is  moved 
sideways,  the  slide  forwards,  and  the  conductors  arranged  direct- 
ly above  the  imprint  of  the  stamp  upon  the  blades. 

The  etching  is  completed  by  using  a  current  which  acts  upon 
the  imprinted  design,  but  leaves  untouched  the  background. 


ELECTROLYTIC  ETCHING  133 

The  material  for  the  protecting  coating  consists  of 

Naphtha i  liter 

Carbon  bisulphide 125  grams. 

Pulverized  resin 2000  grams. 

Cupric  chloride 1500  grams. 

A  thin  layer  of  this  coating  is  placed  upon  the  surface,  the 
stamp  washed  off  with  a  weak  solution  of  caustic  potash,  and  then 
pressed  upon  the  coated  surface.  The  articles  are  then  washed 
with  water  and  the  imprint  of  the  stamp  with  a  weak  solution  of 
ammonium  chloride.  The  articles  are  then  at  once  subjected  to 
the  electrolytic  etching.  The  imprint  of  the  stamp  is  etched  upon 
the  metal  because  the  place  stamped  is  in  conducting  connection 
with  the  current  used.  The  ammonium  chloride  used  in  this  pro- 
cess can  be  replaced  by  common  salt. 

Applications. 

The  process,  as  described,  takes  only  a  short  time.  When  the 
etching  is  completed  the  knives  are  taken  out,  dipped  into  a  solu- 
tion of  caustic  potash  or  soda  in  order  to  dissolve  off  the  coating. 
The  knives  are  then  ready  for  further  treatment. 

The  process  described  allows  of  etching  to  a  sufficient  depth  to 
show  quite  clearly  the  design  of  the  stamp. 

HALL  AND  THORNTON'S  PROCESS. 

Hall  and  Thornton1  have  invented  another  method  of  applying 
anodic  action  in  order  to  produce  points  upon  metallic  rods. 

Many  metals  are  injured  by  the  cutting,  turning,  hammering 
or  rolling  which  they  must  undergo  in  order  to  put  them  into  the 
desired  shape. 

Unavoidable  heating  of  surfaces  which  are  being  worked  can 
easily  draw  the  temper  of  steel  pieces.  To  avoid  this  some  fac- 
tories have  replaced  grinding  by  an  electrolytic  bath  in  which  the 
articles  to  be  worked  are  used  as  anodes  in  order  to  be  thus  re- 
duced to  the  desired  thickness.  In  the  process  being  described 
articles  of  uniform  or  non-uniform  dimensions  may  be  treated 
and  the  desired  removal  of  material  is  controlled  by  raising  or 
lowering  the  level  of  the  electrolyte  or  by  the  corresponding  sink- 
ing or  raising  of  the  articles.  The  articles  treated  are  awls,  need- 

1  German  Patent  87,845,  Aug.  30,  1895  ;  see  also  Zeitschrift  f   Elektrochemie  3,     i  ;- 


134  MANUFACTURE  OF  METALLIC  OBJECTS 

les,  surgical  instruments,  fish  hooks,  umbrella  ribs,  rapiers, 
swords,  spokes  for  bicycles,  forks,  etc.  The  patent  describes  the 
following  apparatus  for  the  carrying  out  of  this  process. 

Apparatus. 

Fig.  77  shows  the  apparatus  for  the  treatment  of  a  series  of 
wire  rods,  which  are  to  be  given  a  tapered  form  by  being  grad- 
ually lifted  out  of  the  solution.  Fig.  78  is  a  plan  of  the  arrange- 
ment of  Fig.  77.  Fig.  79  shows  a  tapered  metallic  rod  produced 


Figs.  77,  78,  79- 

by  this  process.  Fig  80,  the  same  before  being  treated.  Fig.  Si 
is  a  cross-section  on  a  large  scale  of  the  connections  for  one  of  the 
ends  of  the  rod. 


Fig.  80. 


8l- 


The  holder  a  contains  the  electrolyte  or  the  dissolving  fluid  b, 
and  metallic  zinc  is  added  to  the  same,  if  necessary  ;  a±  is  a  stop- 
cock for  running  off  the  solution,  c  and  d  are  conductors  of  the 
current.  The  conducting  pieces,  c±  dly  carry  the  current  from  the 
negative  or  the  positive  pole  of  the  electric  generator  to  c  and  d, 
while  the  contacts  d2  are  connected  to  the  rods  d,  their  ends  lying 
upon  insulating  pieces,  d3.  Upon  the  rods  d  are  yokes  </4  to  which 
are  fastened  the  upper  ends  of  the  hanging  rods  /,  which  form 


ELECTROLYTIC   ETCHING 


135 


the  anodes,  while  the  negative  rod  c,  which  is  likewise  insulated 
at  one  end  is  in  connection  with  a  block  of  carbon  e,  which  forms 
the  electrode.  The  electric  current  enters  the  solution  at  the 
anode  rod  e  and  leaves  the  solution  at  the  carbon  cathode. 

When  rods  or  wires  of  iron  are  to  be  used  the  solution  becomes 
saturated  with  that  metal  which  either  deposits  as  slime  or  is 
deposited  upon  the  cathode.  Instead  of  using  only  one  carbon 
block  as  cathode  a  series  of  such  blocks  may  be  used  connected 
with  the  negative  conductor  of  the  system. 

Fig.  82  shows  the  invention  applied  to  the  pointing  of  metallic 
pins,  needles,  or  the  like.  Fig.  83  is  a  plan  of  Fig.  82.  Fig.  84 
shows  a  needle  before  being  pointed.  Fig.  85  shows  how  needles, 
having  eyes,  can  be  hung  in  order  to  be  pointed  by  the  process. 

a  is  the  containing  vessel,  a±  the  run  off  cock,  and  /  the  articles 
to  be  pointed  by  being  gradually  drawn  out  of  the  solution  b.  d 
is  a  positive  conductor  and  holder  or  the  pieces,  while  e  is  the 
cathode  which  is  hung  to  the  other  conductor  c. 


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Figs.  82,  83,  84,  85,  86. 

Fig.  86  shows  a  sectional  diagram  of  the  apparatus  applied 
to  simultaneously  carrying  out  the  process  in  two  vessels  in  one  of 
which  the  fluid  rises,  while  in  the  other  it  sinks. 


136 


MANUFACTURE  OF  METALLIC  OBJECTS 


Fig.  87  shows  an  apparatus  in  which  the  articles  to  be  pointed 
are  gradually  lifted  out  of  the  solution,  the  level  of  the  fluid  being 
kept  constant. 


Figs.  87,  88,  89,  90,  91,  92,  93,  94. 

a  is  the  containing  vessel  in  which  the  carbon  block  e  is  hung, 
forming  the  cathode  and  connected  with  the  negative  conductor 
c,  f  are  the  articles  to  be  treated  connected  to  the  positive  rod  d 
of  the  frame  gm  The  rising  and  sinking  of  the  frame  is  done  by 
the  spring  j,  or  a  similar  contrivance  fastened  to  the  pulley  and 
whose  motion  can  be  regulated  by  a  clockwork  or  other  mechan- 
ism i. 

Fig.  88  shows  a  process  intended  for  the  simultaneous  use  of 
two  vessels  and  in  which  the  objects  are  alternately  dipped  into 
one  vessel  and  raised  out  of  the  other. 

a  are  the  holders,  g  the  frames,  and  i  the  regulating  arrange- 
ment, /  the  objects  to  be  treated  fastened  to  the  frames.  As  one 
frame  is  raised  out  of  the  liquid  the  other  one  sinks  into  the  liquid. 

Fig.  89  shows  a  further  form  of  the  apparatus  in  which  the 
change  of  level  of  the  liquid  is  attained  by  the  rising  and  lowering 


ELECTROLYTIC   ETCHING  137 

of  a  displacement  block  /.  The  movement  of  this  block  is  either 
regulated  by  clockwork  or  by  other  means  and  produces  a  corre- 
sponding rise  and  fall  of  the  liquid  so  that  the  objects  dip  more  or 
less  into  the  solution. 

Fig.  90  shows  a  tapered  umbrella  rib  or  bicycle  spoke  with  an 
enlargement  allowed  to  remain  at  the  end  for  the  forming  of  a 
head  or  other  purpose. 

Fig.  91  shows  the  original  form  of  this  rib  or  spoke  with  a  nick 
at  the  point  where  the  tapered  end  and  the  head  come  together. 

Fig.  92  shows  a  tube,  the  inner  and  outer  surfaces  of  which  are 
tapered  by  this  process. 

Fig.  93  shows  a  tube  which  is  tapered  only  on  the  inside. 

Fig.  94  finally  shows  a  rod  tapered  in  sections  obtained  by  al- 
lowing the  fluid  to  remain  stationary  at  the  level  where  the  off- 
sets are  to  be  made,  or  by  correspondingly  arresting  the  motion 
of  the  solution  at  these  points. 


XV.    ELECTROLYTIC  ENGRAVING. 


INTRODUCTION. 

We  have  already  said  that  this  process  is  one  in  which  the  work 
of  the  engraver  is  replaced  by  the  use  of  the  electric  current.  It 
has  been  principally  developed  by  Joseph  Rieders1.  So  far,  it  has 
principally  been  applied  to  engraving  on  metals,  and  of  these 
principally  on  iron  and  steel. 

We  will  go  somewhat  into  the  subject  of  metal-engraving  in 
order  that  the  information  to  be  given  may  be  better  understood. 

There  are  to  be  distinguished  three  kinds  of  metallic  engraving. 
The  oldest  application  of  this  work  was  concerned  with  ornament- 
ing useful  objects  in  order  to  increase  their  commercial  value. 
This  original  creative  application  of  the  engraving  art  was  char- 
acteristic of  the  early  times.  The  second  division  of  the  engrav- 
ers work  was  concerned  with  the  finishing  of  the  reliefs  which 
had  been  made  by  casting;  we  call  this  work  chasing  and  the 
artist  a  chaser  or  engraver.  The  third  group  finally  is  concerned 
with  the  manufacture  of  plates  for  printing  which  we  call  copper 
or  steel  engravings.  Wliile  it  would  not  appear  that  the  electro- 
lytic engraving  could  revolutionize  the  field  of  engraving,  as 
above  described,  yet  it  may  become  a  valuable  aid  in  that  part  of 
the  engraving  which  is  concerned  with  printing,  at  least  by  the 
use  of  which  objects  may  be  made  or  embellished  by  the  use  of 
pressure.  Electrolytic  engraving  is  for  this  reason  of  importance 
for  this  part  of  the  engraving  because  it  replaces  expensive  hand 
labor  by  which  dies  and  moulds  must  be  worked  from  the  crude 
piece  of  steel. 

For  a  long  time  the  engraving  art  has  hoped  to  find  in  electro- 
lytic engraving  a  rational  means  of  replacing  the  artistic  work 
of  the  engraver  by  that  of  the  ordinary  workman.  The  work  of 
Jacobi  in  the  field  of  copper  galvanoplastics  raised  the  general 

^lectrochemische  Zeitschrift.  i,  1900 ;  Dr.  G.  I,angbein,  Zeitschr.  f.  Elektrochemie, 
4.  139 ;  6,  328 ;  German  Patent  124,529,  Feb.  20,  1900 ;  Supplementary  to  German 
Patent  95,081,  Feb.  7,  1897. 


ELECTROLYTIC  ENGRAVING 


139 


hope  that  the  further  pursuit  of  this  line  would  lead  to  favorable 
developments  for  the  engraver.  But  up  to  the  present  it  has  not 
become  practicable  to  produce  electrolytically  deposits  of  steel 
of  such  physical  qualities  as  ordinary  steel ;  quite  aside  from  the 
fact  that  the  production  of  heavy  iron  precipitates,  such  as  are  re- 
quired in  coinage  dies  takes  an  enormous  length  of  time.  But  if 
galvanoplastics  is  to  find  use  in  the  coinage  industry  it  can  only 
be  in  the  form  of  steel  galvanoplastics.  But  the  galvanic  steel 
precipitate  lacks  toughness  in  spite  of  the  fact  that  its  hardness  is 
nearly  equal  to  that  of  steel;  this  is  partly  due  to  the  absence  of 
carbon  in  the  iron  precipitated,  which  is  the  characteristic  ingre- 
dient of  steel. 

ENGRAVING  WITH  PARTIAL  COVERING. 

If  there  is  no  possibility  that  electrolytic  precipitation  can  come 
to  the  aid  of  the  coming  art,  yet  in  electrolytic  engraving  there  is 
a  possibility  of  producing  stamping  dies  electrolytically.  The 
above  described  etching  methods  were  only  in  a  few  rare  cases 


Fig.  95.  Fig.  96. 

applicable  to  the  coining  industry.  If  for  instance,  Fig.  95  rep- 
resents a  section  of  an  iron  plate  with  the  surfaces  ab  and  cd  cov- 
ered, then  the  surface  be  can  be  etched.  If  we  afterwards  cover 
the  surface  bef  and  chg  we  can  obtain  a  second  etching  within  the 
limits  fg;  or  altogether  we  obtain  the  form  befghc.  This  process 
is  for  example  practically  used  in  the  manufacture  of  etched 
cliches.  In  Fig.  96  if  it  is  desired  to  etch  out  the  form  as  figured 
it  would  be  necessary  to  coat  over  very  restricted  areas  in  order 
to  obtain  approximately  the  shape  desired.  The  rounded  parts 


140 


MANUFACTURE;  OF  METALLIC  OBJECTS 


in  particular  could  not  be  thus  etched  out  and  would  have  to  be 
engraved  by  hand ;  the  workman  on  which  must  actually  be  an 
artist  in  order  to  finish  the  design. 

ELECTRO-ENGRAVING  PROCESSES. 

We  will  now  pass  to  the  electro-engraving  processes  themselves 
of  such  nature  that  the  use  of  coverings  are  completely  dispensed 
wiih.  The  process  .is  based  upon  the  fundamental  principle  that 
for  the  attainment  of  the  end  sought  it  is  completely  immaterial 
whether  the  places  not  to  be  etched  are  covered  over  or  whether 
the  places  to  be  etched  only  come  in  contact  with  the  etching 
bath.  The  inventor  allows  the  insulation  to  be  done  by  a  layer  of 
air  and  attains  this  end  by  producing,  by  means  of  a  porous  mate 
rial,  a  fluid  surface  which  by  successive  forward  movements  will 
come  more  and  more  into  contact  with  the  metal  until  a  reversed 
relief  is  entirely  in  contact  with  the  metal  surface.  This  will  be 
clear  from  an  inspection  of  Fig.  97.  The  vessel  is  filled  with  am- 

Stee/  Anode' 


Fig-  97- 

monium  chloride  solution  which  may  be  regarded  as  the  electro- 
lyte. The  plaster  block  is  intended  to  take  the  engraving  to  the 
steel  anode  above.  The  cathode  described  by  the  inventor  as  a 
wire  spiral  is  placed  underneath  the  gypsum  block.  As  soon  as 
the  plaster  block  is  saturated  with  the  electrolyte  its  upper  surface 
becomes  in  reality  the  upper  surface  of  the  electrolyte  in  relief, 
acting  as  the  attacking  agent  against  the  steel  anode ;  the  surface 
of  the  plaster  being  solid  prevents  the  pressure  of  the  steel  block 
from  altering  the  surface  of  the  electrolyte  so  that  the  steel  comes 
only  in  contact  with  the  electrolyte  at  the  high  places  of  the  plas- 
ter relief.  The  current  being  then  turned  on,  the  chlorine  liber- 


ELECTROLYTIC  ENGRAVING  14! 

ated  at  the  anode  dissolves  iron  which  diffuses  as  ferric  chloride, 
FeCl3,  into  the  pores  of  the  plaster.  The  weight  of  the  steel 
anode  presses  down  on  the  points  in  relief  upon  the  plaster  block 
as  soon  as  any  appreciable  thickness  of  the  steel  is  dissolved  and 
the  continuance  of  this  pressure  brings  the  anode  and  plaster 
block  into  better  and  better  contact  until  the  whole  of  the  plaster 
block  is  in  contact  with  the  steel  anode. 

RIEDER'S  FIRST  INVESTIGATIONS. 

In  his  first  attempts  with  this  process  Rieder  used  a  steel  plate 
3  mm.  thick  and  his  electrolyte  a  10  per  cent,  solution  of  ammo- 
nium chloride.  The  battery  had  a  tension  of  2  volts.  The  weak 
point  of  this  arrangement  was  that  the  operation  of  the  etching 
process  could  not  be  followed,  since  by  taking  up  and  again  re- 
placing the  steel  block  points  of  contact  were  changed. 

After  this  the  course  of  the  process  was  guessed  at.  After 
about  one  hour's  electrolysis  it  was  found  that  a  black  mud  ap- 
peared at  the  steel  anode,  after  the  removal  of  which  the  details 
of  the  relief  were  to  be  recognized.  It  was,  therefore,  necessary 
to  devise  an  arrangement  which  would  allow  the  mould  and  the 
steel  anode  to  be  separated  during  the  process  in  order  to  be  able 
to  clean  the  anode.  A  quite  simple  model  apparatus  was  devised 
by  which  much  better  results  were  obtained,  from  which  Rieder 
adduced  the  following  fundamental  laws  of  procedure : 
Fundamental  Laws. 

1.  The  carbon  contained  in  the  steel  and  possibly  also  other  ad- 
mixtures insoluble  in  the  electrolyte,  must  be  mechanically  re- 
moved from  the  anode  plate  from  time  to  time  since  they  lie  as  a 
powder  between  the  plate  and  the  model  making  exact  work  im- 
possible.    The  intervals  at  which  this  must  be  done  is  primarily 
dependent  on  the  amount  of  carbon  in  the  steel  to  be  etched. 

2.  The  ammonium  chloride  at  the  surface  of  the  plaster  block 
is  quickly  used  up,  and  since  the  diffusion  through  the  pores  of 
the  plaster  is  much  slower  than  in  a  free  fluid  the  amount  of  am- 
monium chloride  available  at  the  surface  is  far  below  that  re- 
quired by  the  process.    This  condition  requires  the  occasional  re- 
moval of  the  steel  block  at  intervals  dependent  upon  the  relative 
size  of  the  etching  surface  and  the  current  strength  used.     The 


i42  MANUFACTURE;  OF  METALLIC  OBJECTS 

current  density  in  order  to  work  as  fast  as  possible  is  used  as  high 
as  conditions  will  permit  and  taking  this  into  consideration  it  was 
found  that  20  seconds  is  the  maximum  interval  of  working  which 
must  not  be  exceeded. 

Behavior  of  the  Steel  Anodes. 

The  black  mass  mentioned  above  which  lies  between  the  steel 
plate  and  the  plaster  block  is  not  only  carbon  but  largely  ferrous 
oxide.  It  seems  that  as  soon  as  the  chlorine  at  the  surface  of  the 
plaster  model  is  used  up  there  is  no  longer  electrolysis  of  ammo- 
nium chloride,  but  decomposition  of  water  takes  place.  The 
oxygen  thus  liberated  at  the  anode  forms  with  the  iron  an  in- 
soluble ferrous  oxide  which  deposits  upon  the  anode  and  stops  the 
etching.  The  evolution  of  gases  at  the  anode  also  expels  electro- 
lyte from  the  etching  surface  and  produces  irregularities  in  the 
etching. 

The  Plaster  Used. 

Rieder  met  many  difficulties  in  finding  the  most  suitable  com- 
position for  the  plaster  blocks.  At  first  he  used  alabaster  plaster, 
which,  however,  had  the  great  inconvenience  that  as  soon  as  it 
\vas  saturated  with  electrolyte  it  became  extremely  easily  injured 
as  soon  as  the  anode  was  let  down  upon  it.  It  was  hardly  possible 
to  find  a  substitute  for  plaster  since  the  other  self-hardening 
materials  do  not  have  the  porosity  which  makes  gypsum  so  suit- 
able for  this  process.  Rieder  made  investigations,  by  altering  the 
relative  weights  of  water  and  plaster  used  to  find  such  a  composi- 
tion which  would  be  durable  and  yet  porous.  Another  device 
appeared  to  be  that  of  making  several  similar  models  which 
could  replace  each  other  as  soon  as  one  was  injured;  but  this  met 
with  the  difficulty  of  placing  the  models  always  in  exactly  the 
same  position.  He  afterwards  succeeded  by  using  a  special  meth- 
od of  casting  the  plaster,  which  in  combination  with  satisfactory 
tests  upon  mixtures  used  gave  quite  good  results. 

Mechanical  Devices. 

Fig.  98  shows  some  of  the  mechanical  apparatus  of  the  process, 
g  is  a  glass  vessel  with  the  lid  d  having  an  offset  on  which  is 
placed  the  plaster  model  £  surrounded  by  a  rubber  mantel  C.  It 


ELECTROLYTIC  ENGRAVING 


143 


may  be  interesting  to  remark  here  the  manner  in  which  it  is  pos- 
sible to  replace  the  plaster  blocks  in  the  later  machines.  Sev- 
eral rubber  mantels  c  are  made  in  which  the  similar  models  are 
cast  so  that  they  are  fastened  in  the  cover  in  exactly  the  same  posi- 


Fig.  98. 

tion,  to  which  end  a  mark  is  made  upon  the  cover. 

The  anode  to  be  etched  is  at  A.  This  was  an  exactly  cylindri- 
cally  turned  steel  plate  prevented  from  turning  sideways  by  a 
pointer  not  shown  in  the  figure.  The  anode  fits  exactly  into  the 
opening  of  the  cover  d. 

The  apparatus  had  to  be  converted  into  an  automatically  work- 
ing machine,  which  was  done  by  the  firm  of  Dr.  G.  Langbein  & 
Company,  of  Leipsic,  as  shown  in  Fig.  99.  The  description  is 
briefly  as  follows :  The  plaster  mould  is  fastened  by  two  conical 
wedges  into  the  cast  iron  frame  upon  a  vertically  moving  table, 
the  latter  worked  by  an  eccentric.  Above  this  table  is  the  clamp- 
ing plate  to  hold  the  steel  anode  to  be  etched.  The  clamping  plate 
is  likewise  adjustable  and  can  be  fastened  exactly  parallel  to  the 
mould  by  a  suitable  adjustment.  A  carriage  having  a  rotating 
brush  and  movable  by  an  eccentric  cleans  off  the  steel  plate,  the 
brushes  being  washed  off  by  water,  while,  besides  a  sponge  roller 
is  carried  over  the  mould  for  the  purpose  of  wretting  it  with  elec- 
trolyte. 

Action  of  the  Machine. 

The  mould  upon  the  movable  table  is  applied  to  the  plate  to  be 
etched  without  shock  and  as  elastically  as  possible ;  after  being  in 
contact  15  seconds  and  during  which  electrolysis  takes  place  the 
mould  is  lowered  from  contact  with  the  anode  and  the  cleaning 
processes  by  the  brushing  and  sponging  rollers  take  place.  As 
soon  as  the  cleaning  appliances  have  been  withdrawn  the  mould 
is  again  brought  against  the  steel  plate  and  the  operation  repeated. 


144 


MANUFACTURE  OF  METALLIC  OBJECTS 


For  each  machine  there  is  a  mould  casting  arrangement,  in 
which  the  frames  of  the  machine  are  cast  into  place. 

The  Dynamo. 

The  dynamo  used  gives  a  tension  of  12  volts  to  15  volts  and 
the  current  used  for  a  plate  200  x  300  mm.  is  about  50  amperes,  if 


Fig.  99. 

the  whole  surface  of  the  plaster  model  comes  into  contact  with  the 
steel  plate.  An  electrolytic  engraving  plant  of  this  kind  was  ex- 
hibited at  the  Paris  Exposition  in  1900. 

Duration  of  the  Etching. 
According  to  the  depth  of  the  etching  the  operation  may  take 


ELECTROLYTIC  ENGRAVING  145 

more  or  less  time,  about  4  or  5  hours  being  required  for  a  depth 
of  i  mm.,  varying  somewhat  with  the  fineness  of  the  model.  The 
cleaning  of  the  same  can,  if  desired,  be  accomplished  with  the  as- 
sistance of  compressed  air.  If  the  duration  of  etching  is  12  sec- 
onds, some  600  to  800  etching  periods  must  be  used  in  order  to 
etch  to  the  depth  of  I  mm. 

Patent  Claims. 
German  Patent,  95,081,  February  7,  1897. 

1.  The  process  of  forming  reliefs  and  other  shapes  electrolyti- 
•cally  by  using  a  negative  in  the  shape  of  a  porous  mass,  such  as 
plaster,  clay,  or  the  like,  cast  or  cut,  using  the  article  to  be  formed 
as  anode  pressing  lightly  upon  the  forming  side  of  the  porous 
block  saturated  with  a  suitable  electrolyte,   and  a  cathode  im- 
mersed in  the  electrolyte. 

2.  The  apparatus  for  the  carrying  out  of  the  process  of  Claim 
i,  consisting  of  a  porous  block  upon  which  is  a  negative  of  the 
design  to  be  produced  and  whose  forming  surface  rests  with  a 
light  pressure  against  the  anode  to  be  formed,  and  which  is  satu- 
rated with  electrolyte;  the  block  being   further   encased   in  an 
encasing  mantel  and  the  position  of  the  anode  being  assured  by 
guides. 

German  Patent,   124,529,  February  20,   1900;  an  addition  to 
the  previous  patent. 

1.  A  device  for  the  carrying  out  of  the  process  of  forming  re- 
liefs and  other  designs  electrolytically  according  to  patent  95,081, 
•consisting  in  placing  the  negative  upon  a  vertically  moving  table 
.above  which  is  the  anode  so  that  when  the  table  is  lowered  in  the 
manner  provided,  a  slide  carrying  a  cleaning  brush  for  the  anode 
-can  pass  between  the  negative  and  the  anode,  while  a  moistening 
roller  supplies  the  porous  block  with  fresh  electrolyte  in  order  to 
counteract  the  alkalinity  of  the  electrolyte  upon  the  surface  of 
the  negative. 

2.  An  apparatus  for  the  carrying  out  of  the  purposes  of  Claim 
i,  characterized  by  means  for  automatically  raising  the  negative 
.by  means  of  a  lever  as  the  etching  proceeds. 

Manufacture  of  the  Machines. 
The  manufacture  of  electro-engraving  machines  is  in  the  hands 


146  MANUFACTURE:  OF  METAUJC  OBJECTS 

of  the  Elektrogravure  G.  m.  b.  H.,  in  Leipsic,  and  we  take  from 
the  catalogue  of  this  firm  the  following  data  concerning  the  ma- 
chines, their  listing  and  price  : 

Machine. 
No. 


Jngraving  of 
Surface 

Necessary  for          Total  Power 
Etching:.                 used:  H.  P. 

Price  of  the 
complete 

in.m. 

Volts. 

Amperes. 

installation. 

50  X   50 

15 

2  —  3 

O.4O 

$  625.00 

I20X  150 

15 

15 

1.  00 

1125.00 

200  X  300 

15 

30 

£_ 

1-35 

1725.00 

350  X  45° 

15 

DO 

2.50 

The  air  compressor  is  only  used  when  engravings  deeper  than 
3  mm.  are  to  be  made.  When  engraving  not  so  deep  the  cleaning 
by  means  of  the  brush  and  sponge  roller  suffices.  The  price  given 
above  includes  the  air  compressor  and  the  power  data  includes  its 
power  consumption.  If  the  air  compressor  is  not  used  the  price 
of  the  machine  and  its  power  requirement  is  as  follows  : 

For  machines.  Ei-  E2,  E3. 

Deduct  from  price  ----  $100.00  $125.00  $150.00 

Deduct  from  power  ----         0.5  0.75  i.o  H.  P. 

In  the  price  for  these  plants  the  cost  of  the  dynamo  is  not  in- 
cluded, but  the  license  for  using  the  German  Patent  goes  with  the 
machine,  good  for  the  use  of  the  machine  during  the  life  of  the 
patent. 

Auxiliary  Apparatus. 

The  necessary  conditions  for  the  carrying  out  of  electro-en- 
graving is  the  possession  of  an  original  model  of  wax,  plaster, 
wood,  etc.,  from  which  the  necessary  plaster  moulds  needed  for 
the  electro-engraving  can  be  reproduced  in  numerous  duplicates. 
For  these  purposes  a  complete  plant  must  contain  the  following 
auxiliary  apparatus. 

Two  casting  apparatus  for  20  frames  ;  one  drying  oven  for  dry- 
ing the  plaster  moulds  rapidly,  arranged  for  burning  spirits,  petro- 
leum, or  gas. 

Plant  for  Electro-Hngravure. 

Fig.  i  oo  shows  the  ground  plan  for  the  erection  of  an  electro- 
engraving  plant  of  a  capacity  indicated  in  the  table  by  the  figure 
E2.  Such  a  plant  has  been  erected  in  Moscow  by  the  Faberge 
Silverware  House. 


ELECTROLYTIC  ENGRAVING 


Cost  of  Making  Dies. 

The  cost  of  making  finished  electro-engraved  dies  depends  upon 
the  depth  of  etching  and  the  dimensions  of  the  mould.  It  also  de- 
pends on  whether  the  engraving  is  to  be  afterwards  engraved  or 


Fig.  zoo. 

chased,  or  whether  it  is  to  be  ready  for  use  when  it  comes  from 
the  machine. 

Profits. 

The  approximate  estimate  of  the  profits  of  an  electro-engraving 
plant  have  been  made  as  follows  by  the  author : 

The  machine  of  the  size,  E2,  will  produce  about  10  dies  at  once 
having  a  maximum  etched  depth  of  2  millimeters.     These  dies 


148  MANUFACTURE:  OF  METALLIC  OBJECTS 

are  quite  fine  work,  which,  if  made  by  hand,  would  be  worth 
$37.50  apiece. 

FIXED  PLANT. 

i  Electro-engraving  machine,  E2,  having  a  maximum 
engraving   surface   of  200  X  3°°  nim.,    including 

air  compressor $  1750.00 

i  dynamo  machine,  30  amperes,  at  15  volts,  including 

shunt  regulator,  ammeter,  voltmeter,  and  switch-        125.00 
Shafting,  pulleys  and  small  appliances 125.00 

Total  investment  in  plant •$  2000.00 

COST  OF  PRODUCING  TEN  DIES. 
Power,    10  days  of  10  hours  each  ;  equals  150  H.  P. 

hours  at  i^c.  per  H.  P. -hour $  2.25 

i  engraver  for  touching  up  the  dies  at  $1.50  per  day-  •  15.00 

i  moulder  and  i  engineer  for  10  days 21.25 

150  kilos  of  steel  at  $20  per  100  kilos 30.00 

\Q%  sinking  fund  on  the  capital  invested  for  10  days.  6.67 

5%  interest  on  capital  for  10  days 3.33 

Government  tax  50%  on  the  wages 13. 13 


Cost  of  producing  10  stamps $      94.12 

PROFITS. 
Value  of  produce  (one  die  per  day  200  X  3°°  mm.) 

per  year  of  300  working  days  .' $11250.00 

Cost  of  300  dies  according  to  the  above  assumption . .     2823.65 


Leaving  as  yearly  profit $  8426.35 

Corresponding  to  a  dividend  of  420  per  cent. 

It  may  be  said  that  these  figures  make  no  claim  to  be  true  since- 
very  much  depends  on  the  cost  of  labor  for  running  the  machine. 
The  profits  must  be  smaller  when  work  is  produced  which  must 
compete  with  cheap  hand  labor.  With  increasing  fineness  of  the 
work,  however,  the  cost  of  manufacturing  them  by  hand  in- 
creases rapidly  and  the  profits  of  the  electro-engraving  process- 
will  increase  when  producing  such  fine  work. 


APPENDIX, 

TABLE  I. 

STRENGTH    TESTS    OF    GAI/VANOPLASTICAU.Y    FORMED    COPPER    PRINTING 

PLATES. 


53 

Dimen- 

cs 

U 

lllfcC 

25 

-M    rrt 

cd 

M 

tions  of 

Elongation 

-'£ 

"u    • 

S  E^-* 

1JB 

2 

the  strip 

to  the 

il 

«  g 

C  bfi^H  2 

o.  v 

cC 

before 

^ 

I. 

II. 

"C  * 

tt'S  *  o 

5  5 

s 

testing. 

"So 

jp«2 

O 
^j 

3c 

<D 

e. 

c 

w 

"li.Q'  C 

p. 

'C 

"•A 

If 
fa 

l!: 

I. 

II. 

After 

5|«| 

en 

8 

03 

to 

i 

5. 

£ 

B 

breaking. 

T* 

j| 

1-1 

|| 

.ti 

c 
u 

n  which 

5 

* 

1 

u 

1 

Elastic 
I,imit. 

Elastic 
lyimit. 

R) 

I 

Drop- 
ping. 

•C 

| 

" 

'1 

5 

Cfl 

13 

50     100 

1 

— 

u 

tj 

M 

.H 

mm. 

n 

U 

(U 

5 

5    Kg.  per  sp.  centi.1 

% 

* 

be 
X 

O 

mm. 

0.61 

l.OO 

f 

0.71 
0.74 

2838 
3270 

739-5 
845 

950.5  1  0.062 
1080.5  0.070 

0.082 
0.0905 

27.  o5  10.607 

22.5s    :0  677 

6.6 

6.2 

7-9 

7-5 

20    4 

2.22 

1 

0.74 
0.80 
0.73 

3378       7"6.5 
3605.5  '625.5 

3724.5  ;754 

1047      0.067    0.093 
938.5  0.051     0.080 
925      0.056    0.073 

17.6   0.643 
16.6    0.619 
1  6       0.643 

6 

6.2 

5-7 

7-2 

n 

a 

17    7 

10    7 
20    4 

15    3 

0.85 

I.<=0 
0.85 
I.50 
l.OO 
1.00 

1.  50 

2.50 

4.00 

l.OO 

1.50 

I 

0795 

0^ 

1  0.86 

|o.84 
o.845 
jo.865 
0.801 
1.227 
0.84-5 
1.64 

1.  125 
I  OI2 

2855 
3619-5 
2517 
3238 
2500 
3532 
2715 
2440.5 
2941 
2949-5 
2404.5 
2738 
2795-5 

692.5 
566.5 
7H 
552 

710 
520 
482 
509 
472 
489 
444 
517.5 

880.5 
733 
833 
843 
952 

748'-5 
855.5 
678.5 
716.5 
664.5 
727.5 

0.030 
0.041 
0056 

O.O425 

0.053 
0.058 
0.043 
0044 

0.046 

0.0365 
0.044 
0037 
0.0435 

0.070 

0.0555 
0.064 

O.0725 

0.0735 
0.0855 
0.076 
0.054 
0.080 
0.059 
0.068 

0.0745 

30.9    0.596 
27.5°  o  622 
14.95  0.836 

20.2      0  5^35 

6.1     0.889 
10.3     0.752 
26.4    O.6425 
5-7    o.8o75 
26.4    054  15 
25.1     0.6675 
19.45  0.6635 
33-05  0.5205 
28.5°  0.5605 

64 
6.6 

6-7 
5-9 

Is 

6.8 
7-1 
6.7 

I'1 
6.9 

7-9 

n 

i3 

L 

8.1 

8.T 

8.4 
7-9 
8.4 

I  bath  used  a  Fresh, 
long  time.  bal 

3-23 

042 

3013 

513 

820 

o  035 

0.063 

19.4 

0.685 

6.7    7-9 

R 

10     2 

l.OO 

1.50 

0.69 
0.598 

2674 
2803.5 

464 
401.5 

753 
772 

0.0365 

0.0275 

0.06?5 

fj:l» 

o.4865 
0.7625 

6.6 
6.6 

7-7 
7-8 

O 

I 

Nili 

5    i 

1.30 

O 

o.6o5 

o 

2760.5 

364 

596 

0.023 

0.04I5 

19.75 

O-72O5 

7 

8.2 

'•P  £  5  rt'5 

J 

10 

0 

./•i8 

20    4 

l.OO 

1-93 

2802.5 

583 

849-5 

0.052 

0.077 

12.5 

0.827 

7 

8.1 

t   S3  ^  "rt 

ill 

1 

•03 

Ik8 

"8 

-* 

1  'Z  15  3' 

2 



3 

I    J*  *7"   ^i 

2 

0.25 

t 

0,805 
0.795 

2540 
2534 

5/I-5 
503 

9sl'5 

0.042 
0.041 

o.o8c5 

0.085 

1.8 
I 

0*987 

6-5 
6.6 

7-8 
7.8 

III 

5_ 

J 

jt|4j 

— 

— 

— 

1-55 

4230 

733 

921 

0.049 

0.054 

1-5 

0442 

6.7 

7 

jJUl 

ijfevl 

1  1,000  Kg  per  square  centimeter  =  14,300  pounds  per  square  inch. 


I 


TABLE  II. 

CONDUCTIVITY  OF  ELECTROLYTES  WHICH    ARE  USED  IN  THE  MANUFACTURE 

OF  METALLIC  OBJECTS.1 

The  table  refers  to  temperature  of  solutions  of  18°  C. 
/>==  percentage  by  weight  of  anhydrous  salt  in  the  solution. 

=  number  of  gram-equivalents  of  salt  in  a  cubic  centimeter  of  solution. 
=:  specific  gravity  of  the  solution  at  18°  C.,  or  at  15°  C.,  compared  with 

water  at  4°  C. 
r18=  conductivity  of  the  solution  in  reciprocal  ohms  per  cubic  centimeter 

— Vat  i8°c. 

Q ) 

The  temperature  coefficient  gives  in  fractional  parts  of  x^  the  alteratio11 
of  x  for  one  degree,  for  which  is  taken  the  mean  alteration  betwee11 
18°  and  26°. 

Interpolated  values  are  in  parenthesis. 


Elektrolyt 

* 

100017  (m:ilv) 

s,t 

xo^, 

*is     v  di  '22 

2-5 

0.321 

1.0246 

109 

0.0213 

5- 

0.658 

1.0531 

189 

0.0216 

CuSo± 

10. 

T-387 

1.1073 

320 

0.0218 

15. 

2.194 

1.1575 

42  1 

0.0231 

17-5 

2.631 

1.2003 

458 

0.0236 

5 

0.651 

1.0509 

191 

0.0225 

10 

I-37I 

1.1069 

321 

0.0223 

7  <\n 

15 

2.169 

1.1675 

415 

0.0228 

4 

(20) 

3.053               1.2323 

468 

0.0241 

25 

4.040 

1  .3045 

480 

0.0258 

(30) 

5.124               1.3788 

444 

0.0273 

_ 

0-5 

1-0344 

154 

0.0218 

— 

r 

1.0692 

258 

0.0218 

FeSO, 

— 

2 

1.1375 

39° 

0.0223 

— 

3 

I.  2018 

461 

0.0231 

— 

.3.56 

1.2359 

470 

0.0243 



0-5 

1.0379 

153 

0.0231 

NiSO, 

i 

i 

2 

1-0759 
1.1503 

254 
385 

0.0227 
0.0241 



3 

1.2219 

452 

0.0250 

5 

.   0.307 

1.0422 

256              0.0218 

10 

0.641 

1.0893 

476 

0.0217 

(15) 

i.  006 

1.1404 

683 

0.0215 

20 

1.407 

1.1958 

872 

O.O2I2 

(25) 

1.847 

1.2555 

1058 

O.O2IO 

(30) 

2.332 

1.3213 

1239 

O.O2O9 

AgNU% 

(35) 

2.872 

1-3945 

1406 

O.O2O7 

40 

3-477 

1.4773 

1565 

0.0205 

(45) 

4.158 

1.5705 

1716 

0.0204 

(50) 

4.926 

1.6745 

1856 

0.0205 

(55) 

5.791 

1-7895 

1984 

O.O206 

60 

6.764 

1.9158 

2IOI 

O.O2O9 

The  figures  are  mostly  taken  from   the  work  of  Kohlrausch  and  Holborn,  "  Das 
Ceitvermogen  der  Elektrolyte,"  1898. 


Elektrolyt 

\ 

1000  TJ  (m:\lv) 

Stl4 

^ 

JL  (*:)  . 

;r18    *  dt  '22  ™ 

Na^SO, 

5 

0-735 

1.0450 

409 

0.0236 

(Kohlrausch 
8,  1879) 

10 

15 

1.536 
2.4II 

1.0915 
1.1426 

687 
886 

0.0249 
0.0256 

0.5                       1.0302 

298 

0.0241 

(Klein  '1886) 

I. 

1.0602 

508 

0.0242 

2. 

1.1179 

800 

0.0250 

5 

0.873 

1.0510 

263 

0.0226 

10 

1-836 

1.1052 

414 

0.0241 

MgSO, 

15 

2.891 

1.  1602 

480 

0.0252 

(20) 

4.054 

1.2200 

476 

0.0269 

25 

5-342 

I.286I 

4i5 

0.0288 

5 

0.778 

I.O292 

552 

0.0215 

(NH  }.2SO, 

10 

1.  60  1 

I.058I 

1010 

0.0203 

Kohlrauscn 

20 

3-337 

1.1160 

1779 

0.0193 

8,  1879) 

30 

5-322 

1.1730 

2292 

O.Oigi 

31 

5.528 

1.1787 

2321 

O.OI9I 

5 

0.948 

1.0142 

918 

0.0198 

10 

i.923 

1.0289 

1776 

0.0186 

NH.Cl 

15 

2.924 

1.0430 

2596 

0.0171 

20 

3-952 

1.0571 

3365 

0.0161 

25 

5.003 

1.0710 

4025 

0.0154 

KCN 

3-25 

6-5 

0.506 
1.029 

1.0154 
1.0316 

527 
1026 

0.0207 
0.0193 

5 

1.053 

1.0331 

2085 

O.OI2I 

10 

2.176 

1.0673 

39  *  5 

0.0128 

15 

3.376 

1.1036 

5432 

0.0136 

I 

20 
25 

4.655 
6.019 

1.1414 
1.1807 

6527 
7171 

0.0145 
0.0154 

"   „, 

3° 

7.468 

1.2207 

7388 

0.0162 

^S 

35 

9.011 

1.2625 

7243 

0.0170 

*ykrT  ^ 

40 

10.649 

1.3056 

6800 

0.0178 

2  ^ 

(45) 

12.396 

1.3508 

6146 

0.0186 

2    II 

50 

14.258 

1.3984 

5405 

0.0193 

3    > 

(55) 

16.248 

1.4487 

4576 

O.O2OI 

k°   '3 

60 

18.375 

1.5019 

3726 

0.0213 

^  -J? 

65 

20.177 

1.5577 

2905 

0.0230 

cT 

70 

23.047 

1.6146 

2157 

0.0256 

8 

75 

25-592 

1.6734 

1522 

O.O29I 

jw 

80 

28.25 

1.7320 

1105 

0.0349 

85 

30.90 

1.7827 

980 

0.0365 

90 

33-34 

1.8167 

1075 

O.O32O 

95 

35.58 

1.8368 

1025 

O.O279 

(Bock    1887) 
Aquiv. 

0.776 
1.92 

0-377 
0.936 

1.0029 
1.0073 

O.O22 
O.  II 

0.0231]       £> 
0.0143     I       ° 

2.88 

1.409 

1.0109 

O.2I 

O.OIII    [    « 

3.612 

1.771 

1.0131 

0.31 

0.0075]   °i 

3 

152 


MANUFACTURE  OF  METALLIC  OBJECTS 


TABLE  III. 

SPECIFIC  RESISTANCE  OF  A  CUBE  OF  ELECTROLYTE  ONE  DECIMETER  ON 

A  SIDE.     (OHMS). 


1000  rj  (m). 

H,SO,. 

CuSO^ 

iooo7j(m).              ff2SO±. 

CuSO±. 

o.oor 

277.0 

1000.  0 

O.I 

4.444 

22.2 

O.OO2 

143-0 

527.0 

0.2 

2.337 

12.8 

0.005 

58.8 

244.0 

0-3 

1.587 

9-35 

0-5 

0.976 

6.49 

O.OI 

32.2 

139.0 

1.0 

0.504 

3.875 

O.O2 

17-5 

76.9 

2  0 

0.273 

2.497 

o  03 

12.2 

58.8 

3-o 

0.199 

2083 

0.05 

7.87 

38.5 

5.0 

0.148 

IO.O 

0.143 

— 

TABLE  IV. 

WEIGHTS   OF   COPPER   PRECIPITATES   OBTAINED   FROM   ACID   SOLUTIONS. 


Current  density 

used. 


Weight  of  a  square  decimeter  of  the  precipitate  in  grams  after 


Amp.  per  sq.  dm. 

i  hour. 

2  hours. 

5  hours. 

10  hours. 

0-5 
0-75 
1.  00 

0-59 
0.89 
1.18 

I.lS 
I.78 
2.36 

2.96 
4-44 
5-9? 

5-92 

8.87 
11.84 

1-25 
1.50 
1-75 

2.00 

1.48 
1.78 
2.07 
2-37 

2.96 
3.56 
4.14 
4-74 

7.40 
8.88 
10.37 
11.85 

14.80 
17.76 
20.74 
23.70 

2-25 
2.50 

2-75 
3.00 

2.67 
2.96 
3-26 
3-55 

5-34 
5-92 
6.52 
7.10 

13-33 
14.80 
16.28 
17-75 

26.65 
29.60 
32.55 
3S-50 

3-5 
4.0 

4-15 

4-74 

8.30 
9.48 

20.75 

23.70 

41.50 
47-40 

4-5 

5-0 

5  32 
5-90 

10.64 
1  1.  80 

26.60 
29.50 

53-20 
59.00 

5-5 
6.0 

6.50 
7.10 

13.00 
14.20 

32.50 
35-50 

65.00 
71.00 

6-5 

7.0 

7.70 
8.30 

15.40 
1  6.  60 

38.50 
41.50 

77.00 
83.00 

7-5 
8.0 

8.90 
9-45 

17.80 
18.90 

44.50 
47-25 

89.00 
94-50 

8-5 
9.0 

10.05 
10.70 

20.10 

21.40 

50-25 
53-50 

100.50 
107.00 

9-5 

IO.O 

11.25 
ii.  So 

22.50 

23.60 

56.  25 
58.00 

112.50 
1  1  8.00 

APPENDIX 


153 


TABLE  V. 

THICKNESS  OF  COPPER  PRECIPITATES. 


Current 
density 
used. 

O.I 

mm 

O.2 

mm 

Numb 

0.3 
mm 

er  of  h 

0.4 
mm 

ours  required 

0.5        0.6 
mm      mm 

for  a  tl 

0.7 
mm 

lickness 

0.8 
mm 

,of 

0.9 
mm 

I.O 

mm 

Thickness 
of  the 
copper 
precipitate 
in  10  hours 
in  milli- 
meters. 

0-5 
0.75 

I.OO 

I5-I 
IO.I 

7-5 

3°.2 
20.  2 
[5.0 

45-3 
30.6 
22..S 

60.4 
40.4 
30.0 

75-5 
50.5 

37.5 

90.6 
61.2 
45-0 

105.7 
71.0 
52.0 

i20.8 
80.8 
60.0 

135-9 
90.9 

67.5 

I5I.O 
IOI.O 

75-0 

0.0664! 
0.0995  j 
0.133 

1.25 
1.50 

1.75 

2.OO 

6.0 
5-0 
4-3 

3-75 

[2.0 

ro.o 
8.6 
7-5 

18.0 
15.0 
12.9 
H.25 
10.05 
9.00 
825 
7-5 

24.O 
2O.O 
17-2 
I5.0 

13-4 
12.0 
II.  0 
10.  0 

30.0 
25-0 
21.5 
18.75 

36.0 
30.0 
25.8 
22.5 

42.0 
35-0 
30.1 
26.2^ 

48.0 
4O.O 

34-4 
30.0 

26.8 
24.0 

22.0 

20.  0 

54-0 
45-0 
38.7 
33-75 

60.0 
50.0 
43-f> 
37-5 

O.166 
0.199 
0.233 
0.267 

2.25 
2.50 

2.75 
3.00 

3-35 
3.00 

2.75 
2-5 

6.7 
6.0 

5-5 
5-0 

16.75 
15.00 

13-75 
12.5 

20.1 

18.0 
16.5 
15.0 

23-45 

2I.OC 
19.25 
17.5 

30.15 
27.00 

24-75 
22.5 

33-5 
30.0 

27.5 
25.0 

0.299 

0.332 
0.366 

0-399 

3-5 
4.0 

2.15 
1.88 

4-3 
3-76 

6.45 
5-64 

8.6 
7.52 

10-75 
9-4 

12.9 
11.28 

15-5 
I3-I6 

17.2 
15  04 

19-35 
16.92 

21.5 
18.75 

0.466 

0-534 

4-5 
5-0 

1-65 
1-5 

3-3 
3-0 

4-95 
4-5 

6.6 
6.0 

8.25 
7-5 

9-9 
9-6 

U.55 
10.5 

13.2 

12.  0 

14.85 
13.5 

16.5 
15.0 

0.598 
0.664 

5.5 
6.0 

1-35 
1.25 

2.7 

2-5 

4-05 
3-75 

5-4 
5-0 

6-75 
6.25 

8.J 
7.5 

9-45 
8.75 
8.05 
7.56 

10.8 

10.  0 

12.15 
11.25 

13.5 
12.5 

0.732 
0.798 

6-5 
7-0 

I.I5 
1.08 

I.O 

0-93 

2.3 
2.16 

3.45 
3-24 

4.6 
4-32 

5-75 
5-4 

6.9 

6.48 

9.2 
8.62 

10.35 
9-72 
9-o 
8.32 

ii.  5 
10-75 

0.864 
0.930 

7-5 
8.0 

2.O 

1.86 

3-0 
2,79 

4.0 

3-72 

5.o 
4.6 

6.0 
5-58 

7-0 
6.51 

8.0 
7-44 

IO.O 

9-33 

1.  000 

.065 

8.5 
9.0 

0.88 
0.83 

1.76 
1.66 

2.64 
2.49 

2-37 
2.25 

3-52 

3-32 

4-4 
4.15 

5-28 
4.98 

6.16 
5.8i 

7.04 
6.64 

7.92 

7.72 

8.83|       .126 

8.33           .200 

9-5 

10.0 

0.79 
0-75 

1.58 
1.50 

3.i6 
3-0 

3-9 
3-75 

4-74 
4-50 

5.53 
5.25 

6.32 
6.0 

7.06 
6.75 

7-92 

7-5 

.260 
.330 

The  numbers  in  the  above  table  are  only  true  for  homogeneous  current 
distribution  and  do  not  apply  to  edges  or  like  cases  where  the  current  dis- 
tribution may  have  various  values. 

TABLE  VI. 

AUXILIARY  TABLE   FOR  USE  IN   THE  MANUFACTURE  OF   COPPER   WIRE. 


For  wires  of  a 
diameter 
in   millimeters 

Surface  of  one 
meter  length 
in  square 

Current  required  for  one  meter  length  at  a  current 
density  in  amperes  per  square  decimeter  of 

of 

decimeters. 

0.5 

I.O 

i-5 

2.O 

I 
2 

0.31 
0.62 

0.15 
0.30 

0.30 

0.60 

0-45 
0.90 

O.6O 
1.20 

3 

0-93 

o.45 

0.90 

1-35 

1.  80 

4 

1.24 

0.60 

1.  20 

1.  80 

2.40 

5 

1.55 

0.75 

1.50 

2.25 

3.00 

6 

1.86 

0.90 

1.  80 

2.70 

3.60 

7 

2.17 

1.05 

2.10 

3.15 

4.20 

TABLE  VII  (a). 

WEIGHT  OF  SEAMLESS   COPPER   TUBES  PER   RUNNING   METER  IN   KILO- 
GRAMS.    (MADE  BY  THE  ELMORE  PROCESS). 


Inside 
diam- 
eter in 
mm 

i  mm 

Thickness  of  wall  in  millimeters. 

i^  mm  '\Yz  mm:i%  mm    2  mm    2j^  mml  3  mm    3%  mm'  4  mm  i  5  mm 

i                                            j 

3 

0.11 

0.15 

0.19 

0.23 

0.28 

0.39 

0.51 

0.64 

_ 

_ 

4 

.14 

.18 

•23 

.28 

•34 

.46 

•59 

•  74 

— 

— 

5 

.17 

.22 

.28 

•33 

.40 

•53 

.68 

•  84 

1.02 

— 

6 

.20 

.26 

•32 

•38 

•45 

.60 

•  76 

•94 

.13 

1.55 

7 

•23 

.29 

•36 

•43 

•67 

•85 

1.04 

.24 

.70 

8 

•25 

•33 

.40 

•48 

•56 

•74 

•93 

.14 

•36 

•84 

9 

.28 

•36 

•  44 

•53 

.62 

.81 

1.02 

•  24 

•  47 

.98 

10 

•31 

.40 

•49 

•58 

.68 

.88 

.10 

•34 

•58 

2.12 

ii 

12 

•34 
•37 

•43 
•47 

•53 

•57 

a 

•73 
•79 

i:9ol 

•19 
.27 

•43 
•53 

.70 
.81 

.26 

.40 

13 

•  50 

•30 

.61 

•73 

•85 

.07 

•36 

•63 

.92 

•54 

14 

.42 

•54 

.66 

.78 

.90 

•  17 

•44 

•73 

2.04 

.69 

15 

•45 

•57 

.70 

•83 

.96 

.24 

•53 

•83 

•15 

•83 

16 

•48 

.6! 

•  74 

•89 

1.02 

•31 

.6! 

•93 

.26 

•97 

17 

•64 

•78 

•93 

.07 

•38 

.70 

2.03 

•37 

3.11 

iS 

•54 

.68 

•83 

.98 

•13 

•45 

.78 

•13 

•49 

•25 

19 

•57 

•72 

•87 

1.03 

•52 

.87 

•23 

.60 

•39 

20 

•59 

•75 

.08 

•  24 

•59 

•95 

•33 

•  71 

•53 

21 

.62 

•79 

•95 

•13 

•30 

.66 

2.04 

.42 

•83 

.68 

22 

•65 

.82 

1.00 

•  17 

•36 

•73 

.12 

•52 

•94 

.82 

23 

.68 

.86 

.04 

.22 

.80 

.20 

.62 

3.05 

.96 

24 

.71 

.89 

.08 

•27 

•47 

.87 

.29 

.72 

•17 

4.10 

25 

•73 

•93 

.12 

•32 

•53 

•94 

•37 

.82 

.28 

•24 

26 

.76 

.96 

•17 

•37 

•58 

2.01 

•46 

•92 

•36 

•38 

27 

•79 

1.00 

.21 

•42 

.64 

.08 

•  54  - 

3.02 

•  50 

•52 

28 

.82 

•03 

•25 

•47 

.70 

.16 

•63 

.12 

.62 

.66 

29 

•85 

.07 

•29 

•52 

•75 

•23 

•  71 

.22 

•73 

.81 

30 

.88 

.10 

•34 

•57 

.81 

•30 

.80 

•31 

•84 

•95 

31 

.90 

.14 

•38 

.62 

•87 

•37 

.88 

.41 

.96 

5.09 

S2 

•  17 

.42 

•67 

•93 

.44 

•97 

•51 

4.07 

•23 

33 

.96 

.21 

.46 

•  72 

.98 

3.05 

.61 

.18 

•37 

34 

•99 

•25 

•77 

2.04 

•'58 

.14 

•71 

•30 

35 

1.02 

.28 

•55 

.82 

.09 

•65 

.22 

.81 

.41 

.'66 

36 

•05 

•32 

•59 

•  87 

•  15 

•72 

•31 

.91 

•52 

.80 

37 

.07 

•35 

•63 

.92 

.20 

•79 

•39 

4.01 

.64 

•  94 

38 

.10 

•39 

•67 

•97 

.26 

.86 

.48 

.11 

•75 

6.08 

39 

•T3 

.42 

.72 

2.02 

•32 

•93 

.56 

.21 

.86 

.22 

40 

.16 

•  46 

•  76 

.07 

•37 

3.00 

.65 

•30 

.98 

•36 

4i 

.19 

•49 

.80 

.11 

•43 

.07 

•73 

.40 

5.09 

•50 

42 

.22 

•53 

•84 

.16 

•49 

.14 

.82 

•50 

.20 

•64 

43 

.24 

•  56 

.89 

.21 

•54 

.22 

.90 

.60 

•32 

•79 

44 

.27 

.60 

•93 

.26 

.60 

.29 

•99 

.70 

•43 

•93 

45 

•30 

•63 

•97 

•31 

.66 

•36 

4.07 

.80 

•  54 

7.07 

46 

•33 

•67 

2.01 

.36 

•71 

•43 

.16 

.90 

•65 

.21 

47 

•36 

.70 

.06 

.41 

•  77 

•5° 

•24 

5.00 

•77 

•35 

48 

•38 

•74 

.10 

•46 

•83 

•56 

•33 

.10 

.88 

•49 

Inside 
diam- 
eter in 
mm 

Thickness  of  wall  in  millimeters, 
i  mm    ij£  mm  \%  mm  i%  mm    2  mm    2^  mm    3  mm    3%  mm    4  mm 

5  mm 

49 

.41 

.78 

.14 

•  Si 

.88 

.64 

.41 

•  19 

•99 

•63 

50 

•44 

.81 

.18 

.56 

•94 

•  7i 

•50 

•29 

6.11 

•  77 

51 

•47 

•85 

•23 

.61 

3.00 

•  78 

•58 

•39 

.22 

•92 

52 

•50 

.88 

•  27 

.66 

•05 

•85 

.66 

•49 

•33 

8.06 

53 

•53 

.92 

•31 

.71 

.11 

•92 

•75 

•59 

•45 

.20 

54 

•55 

•95 

•35 

•76 

.17 

•99 

•83 

.69 

.56 

•34 

55 
56 

.58 
.61 

2:9o92 

.40 
.44 

.81 
.86 

.22 

.28 

4.06 

•13 

•92 
5.00 

•79 
.89 

.67 

•79 

.48 
.62 

57 

.64 

.06 

.48 

•91 

•34 

.21 

.09 

•99 

.76 

58 

.67 

.09 

•52 

.96 

•39 

.28 

•  17 

6.09 

7.01 

59 

.70 

•56 

3.01 

•45 

•35 

.26 

.18 

.12 

9'.05 

60 

•  72 

.16 

.61 

•05 

•42 

•34 

.28 

.24 

.19 

61 

•75 

.20 

•65 

.10 

•56 

•49 

•43 

•38 

•35 

•33 

62 

•78 

•23 

.69 

•15 

.62 

.56 

•52 

•48 

•46 

•47 

63 

.81 

.27 

•73 

.20 

.68 

•63 

.60 

.58 

•58 

.61 

64 

.84 

.78 

•25 

.72 

.70 

.68 

.68 

•69 

•75 

•34 

.82 

•30 

•79 

•77 

•77 

.78 

.80 

.90 

66 

'.8?9 

.38 

.86 

•35 

•85 

-84 

•85 

.88 

•92 

10.04 

67 

.92 

.41 

.90 

.40 

.90 

•9r 

.  Q  -1 

•98 

8.03 

.18 

68 

•95 

•45 

•95 

•45 

.96 

.98 

6.02 

7.08 

.14 

•32 

69 

.98 

•48 

•99 

•50 

4.01 

5.05 

.11 

.17 

.26 

.46 

70 

2.01 

•52 

3.03 

•55 

.07 

.12 

•19 

.27 

•37 

.60 

71 

.04 

•55 

.07 

.60 

•  13 

•19 

.28 

•37 

.48 

•74 

72 

.06 

•59 

,12 

•65 

.18 

•27 

•36 

•47 

•59 

•  89 

73 

.09 

.62 

.16 

•  70 

.24 

•34 

•45 

•57 

.71 

11.03 

74 

.12 

.66 

.20 

•75 

•30 

.41 

•53 

•  67 

.82 

•  17 

75 

•T5 

.69 

•24 

.80 

•35 

.48 

.62 

•77 

•93 

.31 

76 

.18 

•73 

.29 

•  85 

.41 

•55 

.70 

.87 

9.05 

•  45 

77 

.21 

.76 

•33 

.90 

•47 

.62 

.78 

•97 

.16 

•59 

78 

•23 

.80 

•37 

•95 

•  52 

.69 

•  87 

8.06 

•27 

•73 

79 

.26 

.84 

4.00 

•58 

.76 

•95 

.16 

•39 

.87 

80 

•29 

•  87 

-'46 

.04 

•64 

•83 

7.04 

.26 

•50 

12.02 

Si 

•32 

.91 

•  50 

.09 

.69 

.90 

.12 

•36 

.61 

.16 

82 

•35 

•94 

•54 

.14 

•  74 

•97 

.21 

.46 

•73 

•3° 

83 

•38 

•98 

.58 

•19 

.81 

6.04 

.29 

.56 

.84 

.44 

84 

.40 

3.01 

•63 

.24 

.86 

.11 

.38 

.66 

•95 

•58 

85 
86 

•43 
.46 

3 

.67 

•29 

•34 

•92 
•98 

.18 
.26 

.46 

•  55 

•  76 
.86 

10.07 

.18 

87 

•49 

.12 

•  75 

•39 

5.03 

•33 

•63 

.96 

•29 

13.01 

88 

•52 

•15 

.80 

.44 

.09 

.40 

.72 

9.05 

.40 

•  15 

89 

•55 

•19 

.84 

•49 

•15 

•47 

.80 

•  15 

•  52 

•29 

90 

•57 

.22 

.88 

•54 

.20 

•54 

.89 

•25 

•63 

•43 

9i 

.60 

.26 

•92 

•59 

.26 

.61 

•97 

•35 

•74 

•57 

92 

•63 

.29 

.96 

•64 

•31 

.68 

8.06 

•45 

.86 

•71 

93 

.65 

•33 

4.01 

.69 

•37 

•75 

.14 

•55 

•97 

•85 

94 

.68 

•37 

.05 

•  74 

•43 

.82 

•23 

•65 

11.08 

14.00 

95 

•  7i 

.40 

.09 

•79 

.48 

.89 

.31 

•75 

.20 

.14 

96 

•74 

•44 

•  84 

•54 

.96 

.40 

.85 

•31 

.28 

97 

•  77 

•  47 

.18 

.89 

.60 

7.03 

.48 

•94 

•42 

•42 

156 


MANUFACTURE  OF  METALLIC  OBJECTS 


Inside 
diam- 
eter in 
mm 

i  mm 

Thickness  of  wall  in  mil 
ij^  mmli^  mm  i^  mm'  2  mm    2%  mm 

limeters, 
3  mm  \$%  mm 

4  mm 

5  mm 

98 

.80 

•51 

.22 

•94 

•65 

.10 

•57 

10.04 

•  54 

•56 

99 

.83 

•54 

.26 

•99 

•7i 

.17 

•65 

.14 

.65 

.70 

100 

.86 

•58 

•30 

5.03 

•77 

.24 

•  74 

.24 

.76 

•84 

101 

.88 

.61 

•35 

.08 

.82 

•32 

.82 

•34 

.87 

•99 

102 

•91 

•65 

•39 

•  13 

.88 

•39 

•91 

.44 

•99 

15.13 

103 

•94 

.68 

•43 

.18 

•94 

•46 

•99 

•  54 

12-10 

.27 

104 

•97 

.72 

•47 

•  23 

•99 

•53 

9.08 

•64 

.21 

.41 

105 

3.00 

•75 

•  52 

.28 

6.05 

.60 

.16 

•74 

•33 

•55 

106 

•°3 

•79 

.56 

•33 

.11 

.67 

•25 

.84 

•44 

.69 

107 

•05 

.82 

.60 

•38 

.16 

•74 

•33 

•93 

•55 

•83 

108 

.08 

.86 

.64 

•43 

.22 

.81 

.42 

11.03 

.67 

.98 

109 

.11 

.90 

.69 

.48 

.28 

.88 

•50 

•13 

•  78 

16.12 

no 

.14 

•93 

•73 

•53 

•33 

•95 

•59 

•23 

.89 

.26 

in 

•  17 

•97 

•77 

•58 

•39 

8.02 

•67 

•33 

13.00 

.40 

112 

•*9 

4.00 

.81 

•63 

•45 

.09 

•76 

•43 

.12 

•  54 

113 

.22 

.04 

.86 

.68 

•5° 

.16 

.84 

•53 

•23 

.68 

114 

•25 

.07 

•9° 

•73 

•56 

•23 

•93 

•63 

•34 

.82 

JI5 

.28 

.11 

•94 

•  78 

.61 

•30 

10.01 

•73 

.46 

•97 

116 

•31 

.14 

•98 

•83 

.67 

.38 

.10 

•83 

•57 

17-11 

117 

•34 

.18 

5.03 

.88 

•73 

•45 

.18 

•93 

.68 

•25 

118 

.36 

.21 

.07 

•93 

.78 

•52 

•  27 

12.02 

.80 

•39 

119 

•39 

•25 

.11 

.08 

.84 

•59 

•35 

.12 

•9i 

•53 

120 

•42 

.28 

•  15 

6.03 

.90 

.66 

•  44 

.22 

14.02 

.67 

121 

•45 

•32 

•19 

.07 

•95 

•73 

•52 

•32 

.14 

.81 

122 

.48 

•35 

.24 

.12 

7.01 

.80 

.61 

.42 

•  25 

•95 

123 

•5i 

•39 

.28 

•17 

.07 

•87 

.69 

•52 

•36 

18.09 

124 

•53 

•43 

•32 

.22 

.12 

•94 

•  78 

.62 

.48 

•  23 

125 

•56 

.46 

•36 

•27 

•'7 

9.01 

.86 

.72 

•59 

•37 

126 

•59 

•50 

.41 

•32 

.24 

.08 

•95 

.82 

.70 

•  Si 

127 

.62 

•  53 

•45 

•37 

.29 

•  15 

11  03 

.92 

.82 

•65 

128 

.65 

•57 

•49 

.42 

•34 

.22 

.12 

13.01 

•93 

•79 

I29 

I30 

.68 
.70 

.60 

.64 

$ 

•47 
•  52 

.41 
.46 

.29 

•36 

.20 
.28 

.11 

.21 

15.04 

•  15 

19908 

APPENDIX 


157 


TABLE  VII  (b). 

WEIGHT  OF  SEAMLESS  COPPER  TUBES   PER   RUNNING  METER   IN   KILO- 
GRAMS.    (MADE  BY  THE   ELMORE  PROCESS). 


Inside 
diam- 
eter in 
mm 

Thickness  of  wall  in  millimeters. 
i^  mm    2  mm  [2%  mm    3  mm  '3^  mml  4  mm  j  5  mm     6  mm 

7  mm 

8  mm 

131 

6.56 

7.52 

9.43 

11.3713.31 

15.27 

1923 

23.2527.32 

31.45 

132 

.62 

.57 

•  50 

•  45 

.41 

.38 

•37 

.41 

•51 

.66 

133 

.66 

•63 

.58 

•  54 

•53 

•53 

•55 

.62 

•74 

.90 

*34 

•  71 

.69 

•65 

.62 

•64 

.66 

•7i 

.76 

•94 

32.12 

135 

.76 

•  74 

•  7i 

•  71 

•73 

.76 

.82 

•92 

28.15 

•35 

J36 

.81 

.80 

•78 

.79 

.81 

•83 

•94 

24.08 

•31 

•57 

137 

.86 

.86 

.86 

.88 

.90 

•  93 

20.05 

.21 

.46 

.So 

138 

•9i 

.91 

•9^ 

•97 

14.00  16  04 

.18 

.36 

.70 

33.05 

*39 

.96 

10.00 

12.05 

.11 

•17 

•33 

.60 

•94 

•25 

140 

7.01 

s!o73 

•07 

•  13 

.20 

•29 

•59 

•77 

29.11 

•47 

141 

.06 

.08 

•  14 

.21 

.29 

.40 

.70 

•93 

•29 

.69 

142 

.11 

.14 

.21 

•29 

•39 

•52 

.81 

25.09 

.48 

•93 

^43 

.16 

.20 

.28 

.38 

•49 

•63 

•93^ 

.26 

.68 

34.15 

144 

.21 

•  25 

•35 

•47 

.60 

•  74 

21.06 

•  45 

.89 

•38 

145 

•25 

•31 

.42 

.56 

.70 

•85 

.21 

.61 

30.09 

.61 

146 

•31 

•36 

•49 

.64 

.80 

.96 

•35 

•  78 

.28 

.83 

147 

•35 

.42 

•57 

•73 

.90 

17.07 

•49 

•95 

•48 

35.06 

148 

.41 

.48 

.64 

.82 

15.00 

•T9 

•64 

26.13 

.68 

.29 

149 

•45 

•53 

.70 

.90 

09 

•30 

•  77 

•29 

.88 

•5i 

.150 

•5i 

.60 

•77 

.98 

•19 

.41 

•91 

.46 

31.08 

•73 

IS* 

•  55 

.65 

•85 

13.06 

•29 

•53 

22.05 

•63 

.28 

.96 

152 

.61 

.70 

•92 

.14 

•38 

.64 

.19 

.80 

•47 

36.18 

I53 

•65 

.76 

•99 

.22 

.48 

•75 

•33 

•97 

.66 

.41 

154 

.70 

.82 

11.06 

•31 

•58 

•87 

•47 

27.14 

.86 

.64 

155 

•75 

.87 

•13 

•39 

.68 

•98 

.61 

•3i 

32.06 

.86 

156 

.80 

•93 

.20 

.48 

.78 

18.10 

•  76 

•48 

.26 

37.09 

157 

.85 

.99 

.27 

•57 

.89 

.22 

•91 

.66 

.46 

•32 

158 

.90 

9.05 

•34 

•65 

.98 

•33 

23.05 

.82 

.66 

•55 

159 

•95 

.10 

.41 

•73 

16.08 

.44 

.19 

•99 

.86 

.88 

1  60 

8.00 

•15 

•48 

.82 

.18 

•55 

•33 

28  16 

33.06 

38.01 

161 

•05 

.22 

•56 

.91 

.28 

.66 

•47 

•33 

•25 

•23 

162 

.10 

.27 

•63 

14.00 

•38 

•  77 

.61 

•50 

•45 

•45 

163 

•15 

•32 

.69 

.09 

.48 

.89 

•75 

.67 

•65 

.68 

164 

.20 

•39 

•  76 

•  17 

•58 

19.00 

.89 

.84 

.84 

•9° 

165 

.24 

•  44 

.84 

•25 

.68 

.11 

24.03 

29.01 

34.03 

39.12 

1  66 

•30 

•50 

•9i 

•33 

.78 

.22 

•  17 

.18 

•  23 

•35 

167 

•34 

•55 

n98 

•42 

.88 

•34 

•32 

•35 

•43 

•58 

1  68 

.40 

.61 

12.05 

•50 

•97 

•45 

.46 

•5i 

•63 

.80 

169 

.44 

.67 

.12 

.58 

17.07 

•56 

.60 

.68 

•83 

40.03 

170 

•50 

•72 

•19 

•67 

•17 

.67 

•74 

•85 

35.03 

.26 

171 

•54 

•  78 

.26 

•  76 

.27 

•79 

.88 

30.02 

•23 

•49 

172 

.60 

.84 

•33 

.84 

•37 

.90 

25.04 

•  19 

•42 

.70 

173 

.64 

.89 

.40 

•92 

•47 

20.01 

.20 

•36 

.62 

•91 

174 

.69 

•95 

•47 

15.00 

•57 

.12 

.36 

•53 

.82 

41.12 

175 

•  74 

10.01 

•55 

.09 

•67 

•24 

•53 

•  7i 

36.02 

•34 

Inside 
diam- 
eter in 
mm 

Thickness  of  wall  in  millimeters 
\Y±  mm    2  mm    2%  mm    3  mm    3^  mm    4  mm      5  mm 

6  mm 

7  mm     8  mm 

176 

•79 

.06 

.61 

•17 

.76 

•35 

•  65 

•87 

.21 

•57 

177 

.84 

.12 

.68 

.26 

86 

.46 

•77 

31.04 

.41 

.81 

I78 

.89 

.18 

•75 

•35 

.96 

•57 

•89 

.21 

.61 

42.05 

179 

•94 

•23 

•83 

.44 

18.06 

.69 

26.02 

•38 

.81 

•29 

i  So 

•99 

.29 

.90 

•53 

.16 

.81 

•15 

•  55 

37.01 

•53 

181 

9.04 

•34 

•97 

.61 

•25 

.92 

.29 

•  72 

.21 

•75 

182 

.09 

.40 

13.04 

.69 

•35 

21.03 

•43    !     -89 

.41 

•97 

183 

.14 

.46 

.10 

•  77 

•45 

.14 

•57 

32.06 

.62 

43.19 

184 

•19 

.51 

.18 

•  85 

•55 

•25 

•23 

•83 

.41 

185 

•23 

•58 

•25 

•93 

•65 

•36 

'85 

.40 

38.04 

•63 

186 

.29 

•63 

•32 

16.01 

•75 

•47 

•99 

•57        -25 

.86 

187 

•33 

.68 

•39 

.10 

•85 

•58 

27.13 

.74        .46    44.09 

1  88 

•39 

•74 

.46 

.18 

•95 

.70 

•  27 

.91        .67        .32 

189 

•43 

.80 

•54 

•  27 

19.05 

.82 

•42 

33.09     .88 

•55 

190 

•49 

•85 

.60 

•37 

•  15 

•94 

•57 

.25    39.09 

191 

•53 

•91 

•67 

•45 

.24 

22.05 

7i 

•42 

.27    45.00 

192 

•59 

.96 

•74 

•53 

•34 

.16 

'85 

•59 

•45 

.22 

•63 

11.03 

.82 

.61 

•44 

•27 

•99 

•76 

.64 

•44 

194 
195 

.68 
•73 

.08 
•  13 

.89 
.96 

.69 

•77 

•54 
•64 

•38 
•49 

28.13 

•27 

349130 

40.02 

•  67 
.90 

196 

•78 

.20 

14.03 

.86 

•  74 

.60 

.41 

.27   |     .21    46.13 

197 

•83 

•  25 

.09 

•95 

•84 

•  72 

•55 

•44 

.40 

•  36 

198 

.88 

•30 

•  17 

17.04 

•94 

•84 

.69 

.61 

•59 

•59 

199 

•93 

•36 

•  24 

.13    20.04 

.96 

•83 

•78 

•  78 

.82 

200 

•98 

.42 

•3i 

.22 

.14 

23.08 

•98 

•95 

•97 

47.05 

201 

10.03 

•47 

•38 

•30 

•24 

•19 

29.12 

35.12 

41.16 

.27  ' 

202 

.08 

•53 

•45 

•38 

•34 

•30 

.26 

.29 

•35 

•49 

203 

•13 

•59 

•  52 

.46 

.44 

.41 

.40 

.46 

•55 

•  71 

204 

.18 

•65 

.60 

•55 

•54 

•52 

•54 

•63 

•75 

•93 

205 

•23 

.70 

.66 

•63 

.64 

•63 

.68 

.80 

•  95    48.16 

206 

.28 

•75 

•73 

.72 

•  74 

•  74 

.82 

.97   '42.15      .39 

207 

•33 

.81 

.80 

.80 

•  84 

•85 

.96   ;36:i4     .35 

.62 

208 

•38 

•87 

.88 

•89 

•94 

.96 

30.10 

.31 

•55 

•85 

209 

•43 

•93 

•95 

•97 

21.0324.08 

.24 

.48 

.75    49.08 

210 

.48 

•99 

15.03 

18.06 

•13 

.20 

•39 

•65 

•95 

•31 

211 

•53 

12.05 

.10 

.14 

•23 

•31 

•53 

.81 

43.14 

•53 

212 

•58 

.10 

.16 

•23 

•33 

.42 

.67 

.98 

•33 

•75 

213 

•63 

•  '5 

•23 

•32 

•43 

•53 

.81 

37.15 

•53 

•97 

214 

.68 

.21 

.41 

•53 

.64 

•95 

•32 

.73    50  20 

215 

•73 

.26 

^38 

•49 

•63 

•75 

31.09 

•49 

•93 

•43 

216 

.78 

•32 

.46 

•58 

•73 

.86 

•23 

.66 

44.13 

.66 

217 

.83 

•38 

•53 

•67 

•83 

.98 

•37 

•83 

•33 

•89 

218 

.88 

.44 

.60 

•75 

•93 

25.10 

•52 

38.00 

•53 

51.12 

219 

•93 

•50 

•67 

•83 

22.03 

.22 

.67 

•  17 

•73 

•35 

220 

•99 

•56 

•74 

•92 

•13 

•34 

.82 

•34 

•93 

•58 

221 

11.03 

.61 

.81 

19.00 

•23 

•45 

.96 

•50 

45.12 

.80 

222        j       .07 

.66 

.88 

.08 

•32 

•  56 

32.10 

•67 

.31    52.02 

223 
224 

.12 

.18 

.72 
•  78 

A 

.16 
•  25 

•42 
•52 

•  67 
.78 

.24 
•38 

.84 
39.01 

|i 

•  24 
•46 

APPENDIX 


159 


Inside 
diam- 
eter in 
mm 

i%  mm    2  mm 

•2.yz  mm 

Thickness  of  wall  in  m 
3  mm    3%  mm    4  mm 

illimeters. 

5  mm       6  mm 

I 

7  mm    1     8  mm 

225 

•23 

•83 

.08 

•33 

.62 

•89 

•52 

.18 

•91 

.68 

226 

.28 

.89 

•J5 

.42 

•72 

26.00 

.66 

•35 

46.11 

•91 

227 

•33 

•95 

.22 

•50 

.82 

.11 

.80 

•52 

•3i 

53.14 

228 

.38 

13.01 

.29 

•59 

.92 

.22 

•94 

.69 

.51 

•37 

229 

•43 

.06 

•36 

.67 

23.01 

•34 

33.08 

.86 

•  7i 

.60 

230 

.48 

.12 

•43 

•  76 

.11 

•46 

.22 

40.03 

•9i 

•83 

240 

•97 

.69 

17.15 

20.61 

24.10 

27.59 

34.63 

41.73 

48.89 

56.58 

250 

12.46 

14.25 

•85 

21.46 

25.09 

28.72 

36.05    43.43 

50.87 

58.34 

260 

.81 

18.56 

22.31 

26.08 

29.8537.46!  45.13 

52.85    60.60 

270 



15.38 

19.27 

23.16 

27.07 

30.9838.87    46.82 

54.83    62.87 

280 



•95 

.96 

24.00 

28.05 

32.11 

40.28    48  52 

56.81 

65.12 

290 



16.52 

20.68 

•85 

29.05 

33.2541.70    50.21 

58.79 

67.38 

300 

— 

17.08 

21.39 

25.70 

30.04 

3438 

43.11     51.91 

60.76 

69.66 

310 



•65 

22.10 

26.55 

31.03 

35.51 

44.53 

53.61 

62.74 

71.93 

320 



18.21 

22.81 

27.40 

32.02 

36.6445.95 

55.31 

64.72 

74.19 

33° 



•77 

23.51 

28.25 

33.01 

37.7747.36 

5700 

66.70 

76.45 

340 



19.34 

24.22 

29.09 

34.0038.9048.77 

58.70 

68.68 

78.72 

350 

— 

•91 

24.92 

•94 

34.99 

40.0450.19 

60.39 

70.66 

80.98 

360 

— 

20.47 

25.63 

30.7935.9841.1751.60 

62  09 

72.64 

83.24 

370 



21.03 

26.38 

31.64 

36.97 

42.3053.01 

63.79 

74.62 

85.50 

380 

— 

.60 

27.0432.49 

37.9643.43 

54.43 

65.48 

76.60 

87.76 

39° 

— 

22.17 

•75 

33.34 

38.95 

44.5655.84 

67.18 

78.57 

90.03 

400 

— 

•73 

28.46 

34.18 

39.9445.69 

57.26 

68.88 

80.55 

92.29 

410 

— 

23.30 

29.1635.03 

40.9346.82 

58.67 

70.57 

82.53 

94.55 

420 



.86 

.87 

.88 

41.91 

47.95 

60.08 

72  27 

84.51 

96.81 

430 

— 

24.43 

30.5836.73 

42.9049.08 

61.50 

73.97 

86.49 

99.07 

440 

— 

25.00 

31.2937.5843.89 

50.22 

62.91    75.66    88.47 

101.34 

450 

— 

•56 

32.0038.43 

44.88 

51.35 

64.32    77.36    90.45 

103.60 

460 

— 

26.13 

.70 

39.2745.87 

52.4865.74    79.06    92.43 

105.86 

470 



.69 

33.4040.12 

46.86 

53.61 

67.14    80.75!   94.41 

108.12 

480 



27.26 

34.11 

.97 

47.85 

54.7468.57    82.45    96.39 

110.38 

490 



.82 

34.82  41  .'82 

48.8455.87 

69.98 

84.14    98.37 

112.65 

500 



28.39 

35.5342.67 

49.83 

57.00 

71.39    85.84100.35 

114.91 

600 

— 

34.0542.60 

51.15 

59.73 

68.30 

85.54102.81  120.14 

137.53 

USTDKX  OF  NAMES. 


Acheson 76 

Anderson 39 

Andreoli 78 

Bauer 39 

Brandt 69 

Brown 122, 129 

Buchholz 9 

Burdette 131 

Burgess .' 45 

Chassy 3 

Cowper-Col<-s ' 64,  91.  108 

Davis 106 

Dessolle .' 63 

Dumoulin 42,  125 

Electro-Metallurgical  Co 46 

Electricitats-Aktien-G.,  V.  Schuckert  &  Co • 52 

E'ektrogravure  G.  I<td.  Elmore 45,  75,  105,  117 

Eltnore,  German  and  Austro- Hungarian  Co 45,  47,  49,  53,  108 

Elkington 76 

Edruweit 61,  70 

Engelhart 38,  46,  10,  104 

Evans 106 

Fletcher 38,  91 

Foerster 4,  22,  23,  26 

Forsyth gt 

Fox 76 

Gerhardi  &  Co 49 

Hall I33 

Hampe ' 26 

Hartig 22 

Haubold IO6 

Hittorf.    .  » 


Holborn 


29 


44 


Holl j*> 

Hoepfner 55 

Huber 60 

Hiibl,  von 6,  15,  25 

Jakobi i 

Jordan i 

Kennedy 122 

Kick I5 

KirchofT 37 

Klein 93 

Kohlrausch 29 

Krueger .  IO6 


1 62  INDEX    OF    NAMES 

I^andauer  &  Co 64 

I<angbein 93,  138 

Leuchtenberg : 25 

Magnus 

Meidinger  ...          15 

Murray '.  6 

Nawrocki 69 

Nussbaum 46,  100 

Perner 69 

Peters 52 

Pfanhauser  .....          27,  42 

Polenz 23 

Preschlin 49,  108 

Reinfeld 44,  6 1 

Rieders 72,  130,  "38,  141 

Sachs 6o 

Sanders ....          84 

Schroeder •  71 

Schuckert  &  Co 52 

Searchlight  Syndicate .   .  116 

Seedel  22 

Soc.  Syndicat  Gerard 54 

Soc.  Cuivres  de  France 43,  I23 

Smee '5 

Spencer l 

Streintz 7* 

Sutherland 43,  I05 

Swan 72,  78 

Tavernier 77 

Thornton *33 

Ullmann 6 

Watt I22 

Wood 43,  69 

Wurtemburg  Metal  Co 4° 


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